Sourdough Onion Focaccia

Featured in: Hearty Comfort Food

Experience a light and chewy sourdough focaccia, crafted with a long fermentation and gentle stretch and folds for structure. Sweet caramelized onions add depth, while sea salt and optional rosemary enhance the rustic aroma. The dough’s overnight rest helps develop rich flavor and tenderness. This Italian-style bread pairs beautifully with meals or as a standalone snack, offering a delightful balance of crisp edges and soft, airy crumb.

Updated on Mon, 16 Feb 2026 11:11:00 GMT
Golden sourdough focaccia with caramelized onions, baked to perfection and topped with sea salt and rosemary. Save
Golden sourdough focaccia with caramelized onions, baked to perfection and topped with sea salt and rosemary. | dashnosh.com

My neighbor brought over a warm slice of focaccia one afternoon, and I still remember the way the dimpled surface glistened with olive oil under the kitchen light. The caramelized onions melted on my tongue, and I thought, "I have to figure out how to make this." Years later, after a few burnt batches and plenty of patience with my sourdough starter, I finally nailed it—and honestly, it's become my go-to bread for impressing people without breaking a sweat.

I made this for a dinner party once, pulling it straight from the oven just as guests arrived, and the moment they walked in, they stopped talking mid-sentence. There's something about fresh focaccia—the way it cracks when you tear into it, the steam rising up—that makes people feel genuinely welcomed. That night, this bread became the star of the table, not the side dish.

Ingredients

  • Active sourdough starter (100 g at 100% hydration): This is your leavening agent and flavor foundation; if your starter isn't bubbly and active, give it a few more hours at room temperature to wake up properly.
  • Bread flour (400 g): The higher protein content builds structure and creates that chewy, open crumb you want in focaccia.
  • Lukewarm water (300 ml): This hydration level creates an extensible dough that's forgiving to work with; use filtered water if your tap water is heavily chlorinated, as it can slow fermentation.
  • Fine sea salt (10 g): Add this after the autolyse to avoid inhibiting gluten development in those early stages.
  • Extra-virgin olive oil (20 ml for dough, plus more for pan and topping): Quality matters here because the oil is a main flavor player; use one you actually enjoy tasting straight from the bottle.
  • Yellow onions (2 medium, thinly sliced): Low and slow caramelization transforms them into glossy, sweet strands that cling beautifully to the dimpled surface.
  • Flaky sea salt (1 tsp) and fresh rosemary (optional): These finishing touches provide textural contrast and herbaceous brightness that prevents the bread from feeling one-dimensional.

Instructions

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Mix and rest the base:
Combine your active starter, flour, and water in a large bowl until everything is shaggy and no dry flour remains. Cover and let it sit for 30 minutes—this autolyse period allows the flour to fully hydrate and makes the dough easier to work with once you add salt.
Incorporate salt and oil:
Wet your hand, add the salt and olive oil to the dough, and squeeze it through with your fingers until fully incorporated. It'll feel slippery and slightly fragile, which is exactly right.
Build gluten with stretch and folds:
Over the next 2 hours, every 30 minutes, grab one side of the dough, stretch it up, and fold it over itself—repeat this from all four sides. You'll feel the dough become stronger and more cohesive with each set; these folds replace kneading and create the structure you need.
First rise:
Cover the bowl and let the dough rise at room temperature for 6 to 8 hours until roughly doubled. The exact timing depends on your kitchen temperature, so trust your eyes over the clock.
Shape into the pan:
Generously oil your 9x13-inch baking pan to prevent sticking. With oiled hands, gently transfer the dough and lightly stretch and press it to fit the pan, being careful not to knock out all the air you've built up.
Cold final proof:
Cover the pan and refrigerate overnight (8 to 12 hours). This slow fermentation develops deeper flavor and makes the dough easier to handle and dimple.
Meanwhile, caramelize the onions:
Heat 1 tablespoon of olive oil in a skillet over medium-low heat, add your thinly sliced onions, and stir occasionally for 20 to 25 minutes until they're golden, soft, and smelling absolutely incredible. They should shrink down to about one-quarter their original volume—be patient, rushing this ruins the magic.
Bring dough to room temperature:
Remove the dough from the refrigerator about 1 hour before baking so it can warm up slightly and become easier to dimple.
Add the toppings:
Preheat your oven to 220°C (425°F). With slightly oiled fingertips, press dimples all across the dough surface—don't be shy, these dimples catch the oil and create textural interest. Drizzle lightly with olive oil, scatter your cooled caramelized onions evenly, sprinkle flaky sea salt, and add rosemary and pepper if using.
Bake to golden:
Bake for 25 to 30 minutes until the edges are crispy and deeply golden and the top is set. You're looking for a bread that feels sturdy, not soft or pale.
Cool and serve:
Let it cool for a few minutes on the pan—this allows the bottom to set—then slice and serve warm while the interior is still slightly steamy.
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The first time someone asked for seconds and then a slice to take home, I realized this bread had crossed from recipe to ritual. It's become the thing I make when I want to show up for people, and that matters more than any perfect crust or perfect rise.

Understanding Sourdough Fermentation

Sourdough isn't complicated, but it does reward attention and observation over strict timing. Your kitchen temperature, the strength of your starter, and even the humidity in the air will shift how fast your dough rises, so learning to read the dough's behavior becomes more useful than any timer. When the dough has roughly doubled and shows a gentle dome with a slight jiggle, you're in the right window, not a minute earlier or later necessarily.

The Secret to Perfect Caramelization

Caramelizing onions is meditative and requires patience that our instant-everything culture doesn't often reward. The Maillard reaction and gradual moisture loss turn sulfurous raw onions into silky sweetness, and there's no shortcut—no high heat, no rushing. Once they're cool and tucked onto your dimpled dough, they become a flavor anchor that makes people stop and ask what makes your focaccia taste like that.

Storing and Reheating Like a Pro

Focaccia stays fresh for a day or two wrapped loosely at room temperature, though honestly, it rarely lasts that long in my house. If you do have leftovers, a quick reheat in a toaster oven at 160°C (320°F) for 5 to 10 minutes brings back the crispy edges and softens the interior without drying it out—much better than microwaving, which turns it to rubber.

  • Wrap cooled focaccia in parchment, then foil, if storing in the refrigerator for up to a week.
  • Frozen focaccia thaws at room temperature and reheats beautifully, giving you fresh-tasting bread anytime.
  • Leftover caramelized onions are excellent on grilled cheese, in a quesadilla, or on top of roasted vegetables.
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Chewy sourdough onion focaccia bread, golden and crisp, with sweet onions and a sprinkle of sea salt. Save
Chewy sourdough onion focaccia bread, golden and crisp, with sweet onions and a sprinkle of sea salt. | dashnosh.com

This focaccia taught me that good bread doesn't need to be complicated or stressful; it just needs time, a few honest ingredients, and your gentle attention. Make it once, and you'll understand why people have been baking bread since the dawn of civilization.

Kitchen Q&A

What makes sourdough focaccia different from regular focaccia?

Sourdough focaccia uses a natural starter, which adds a tangy flavor and contributes to a chewier texture and better keeping quality compared to yeast-only versions.

How do I caramelize onions for the topping?

Slice onions thinly and cook slowly in olive oil over medium-low heat, stirring occasionally until they turn golden and soft, which usually takes 20–25 minutes.

Why is the dough refrigerated overnight?

Refrigeration slows fermentation, enhancing flavor complexity and improving the focaccia’s texture by allowing gluten to relax and flavors to meld.

Can I add other toppings besides onions?

Yes, additions like sliced olives or sun-dried tomatoes work well to complement the caramelized onions and add extra flavor layers.

How should I store leftovers?

Keep leftovers in an airtight container at room temperature or lightly wrap and reheat in a toaster oven to restore crispness before serving.

What is the best way to bake focaccia evenly?

Ensure even dimpling of the dough and use a well-oiled pan. Preheating the oven to a high temperature helps achieve a golden crust with a soft crumb.

Sourdough Onion Focaccia

Airy sourdough focaccia enriched with caramelized onions and sea salt for a crisp, flavorful bread.

Prep Duration
25 min
Cook Duration
30 min
Complete Duration
55 min
Created by Tyler Morgan

Recipe Type Hearty Comfort Food

Skill Level Medium

Cultural Heritage Italian

Output 12 Portion Size

Nutritional Categories Plant-based, No Dairy

What You'll Need

Sourdough Starter

01 3.5 oz active sourdough starter (100% hydration)

Dough

01 14 oz bread flour
02 10 fl oz lukewarm water
03 0.35 oz fine sea salt
04 0.68 fl oz extra-virgin olive oil

Topping

01 2 medium yellow onions, thinly sliced
02 1 tbsp olive oil
03 1 tsp flaky sea salt
04 1 tsp fresh rosemary leaves
05 Freshly ground black pepper

Method

Step 01

Autolyse the Dough: In a large bowl, combine sourdough starter, bread flour, and lukewarm water until a shaggy dough forms. Cover and rest for 30 minutes.

Step 02

Incorporate Salt and Oil: Add fine sea salt and extra-virgin olive oil to the dough. Mix thoroughly until fully incorporated.

Step 03

Build Gluten Structure: Over 2 hours, perform 3 to 4 sets of stretch and folds at 30-minute intervals to develop gluten strength. Perform each set by stretching the dough from edges toward center.

Step 04

Bulk Fermentation: Cover the bowl and allow the dough to rise at room temperature for 6 to 8 hours until doubled in volume.

Step 05

Shape and Pan Preparation: Generously oil a 9x13-inch baking pan. Transfer the dough to the pan with minimal deflation. Using oiled fingers, gently stretch and press the dough to fill the pan evenly.

Step 06

Cold Fermentation: Cover the pan and refrigerate for 8 to 12 hours overnight to develop flavor complexity and achieve superior texture.

Step 07

Caramelize Onions: While dough chills, heat 1 tbsp olive oil in a skillet over medium-low heat. Add sliced onions and cook with occasional stirring for 20 to 25 minutes until deeply golden, tender, and caramelized. Cool completely before use.

Step 08

Temper the Dough: Remove dough from refrigeration and allow it to reach room temperature, approximately 1 hour, to ensure even oven spring.

Step 09

Final Assembly: Preheat oven to 425°F. Using your fingertips, create dimples across the dough surface. Drizzle with additional olive oil, then distribute caramelized onions, flaky sea salt, rosemary, and black pepper evenly over the surface.

Step 10

Bake Until Golden: Bake for 25 to 30 minutes until the focaccia achieves a deep golden-brown color with crisp edges.

Step 11

Cool and Serve: Allow the focaccia to cool slightly before slicing and serving warm.

Kitchen Tools Needed

  • Large mixing bowl
  • 9x13-inch baking pan
  • Skillet
  • Spatula
  • Measuring cups and spoons

Allergy Alerts

Review ingredients carefully for potential allergens and seek professional medical guidance if concerned.
  • Contains wheat and gluten
  • Verify sourdough starter and all ingredients are free from cross-contamination allergens

Nutrition Details (serving size)

Numbers shown are estimates only - consult healthcare providers for specific advice.
  • Energy: 180
  • Fats: 4 g
  • Carbohydrates: 32 g
  • Proteins: 4 g