Sourdough Onion Focaccia Bread (Printable Version)

Chewy sourdough focaccia with caramelized onions and sea salt offers bakery-quality texture and flavor.

# What You'll Need:

→ Sourdough Starter

01 - 3.5 oz active sourdough starter at 100% hydration

→ Dough

02 - 14.1 oz bread flour
03 - 10.1 fl oz lukewarm water
04 - 0.35 oz fine sea salt
05 - 0.68 fl oz extra-virgin olive oil

→ Topping

06 - 2 medium yellow onions, thinly sliced
07 - 1 tbsp olive oil
08 - 1 tsp flaky sea salt
09 - 1 tsp fresh rosemary leaves, optional
10 - Freshly ground black pepper to taste, optional

# How-To Steps:

01 - In a large mixing bowl, combine sourdough starter, bread flour, and lukewarm water until a shaggy dough forms. Cover and let rest for 30 minutes without mixing.
02 - Add fine sea salt and extra-virgin olive oil to the dough. Mix thoroughly until all ingredients are fully incorporated.
03 - Perform 3 to 4 sets of stretch and fold movements at 30-minute intervals over the next 2 hours to develop gluten strength. Use wet hands to gently stretch the dough from the sides and fold it toward the center.
04 - Cover the bowl and allow the dough to rise at room temperature for 6 to 8 hours until volume approximately doubles.
05 - Generously oil a 9x13-inch baking pan. Gently transfer the dough to the pan without deflating it. Using oiled fingers, stretch and press the dough to fill the pan evenly.
06 - Cover the pan with plastic wrap and refrigerate for 8 to 12 hours to develop flavor and improve texture.
07 - Heat 1 tbsp olive oil in a skillet over medium-low heat. Add sliced onions and cook, stirring occasionally, for 20 to 25 minutes until golden, soft, and sweet. Transfer to a plate and cool completely.
08 - Remove the dough from refrigeration and let it rest at room temperature for approximately 1 hour before baking.
09 - Preheat oven to 425°F. Using your fingertips, gently dimple the entire dough surface. Drizzle lightly with additional olive oil. Distribute caramelized onions evenly across the surface. Finish with sea salt, rosemary, and freshly ground black pepper if desired.
10 - Bake for 25 to 30 minutes until the focaccia develops a golden-brown crust and the edges are crispy.
11 - Remove from oven and allow to cool slightly before slicing and serving warm.

# Expert Advice:

01 -
  • The overnight cold fermentation means you're essentially letting flavor develop while you sleep, which feels like cheating but tastes incredibly honest.
  • Those caramelized onions transform something so ordinary into something people will ask you about by name.
  • It's forgiving enough for a second attempt if your first rise doesn't go perfectly, but impressive enough to serve at a dinner where people actually notice what they're eating.
02 -
  • The overnight cold fermentation isn't optional if you want real flavor—room temperature fermentation alone creates a technically correct focaccia that tastes like cardboard by comparison.
  • Caramelized onions take longer than you think, but they're impossible to rush without burning them; trust the process and don't turn up the heat.
  • Sourdough starter strength varies, so if your dough hasn't noticeably risen after 6 hours at room temperature, give it another 1–2 hours instead of panicking.
03 -
  • If you only have room-temperature water, let it sit with your sourdough starter for a few minutes before adding flour—this helps activate the starter and jumpstart fermentation.
  • The dimples should go about halfway into the dough's thickness; if you press all the way through, you'll deflate the structure rather than create character.
  • Save a piece of today's dough to use as a preferment next time, which deepens flavor even more than starting with just your sourdough starter.
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