Sourdough Onion Focaccia Bread (Printable)

Airy sourdough focaccia with sweet caramelized onions and a hint of sea salt, perfect for savory occasions.

# What You'll Need:

→ Sourdough Starter

01 - 3.5 oz active sourdough starter (100% hydration)

→ Dough

02 - 14 oz bread flour
03 - 10 fl oz lukewarm water
04 - 0.35 oz fine sea salt
05 - 0.67 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 (optional)

# Directions:

01 - In a large bowl, combine sourdough starter, bread flour, and water, stirring until a shaggy dough forms. Cover and rest for 30 minutes.
02 - Add fine sea salt and extra-virgin olive oil to the dough and mix thoroughly until fully incorporated.
03 - Perform 3 to 4 sets of stretch and fold techniques every 30 minutes over the next 2 hours to develop gluten strength.
04 - Cover the bowl and allow the dough to rise at room temperature for 6 to 8 hours until approximately doubled in volume.
05 - Generously oil a 9x13-inch baking pan. Gently transfer the dough to the pan without deflating, then use oiled fingers to stretch and press it evenly to fill the pan.
06 - Cover the shaped dough and refrigerate for 8 to 12 hours overnight for enhanced flavor development and optimal 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 deeply golden, tender, and sweet. Transfer to a plate and cool completely.
08 - Remove the dough from the refrigerator and allow it to rest at room temperature for approximately 1 hour.
09 - Preheat oven to 425°F. Using your fingertips, gently dimple the dough surface. Drizzle with additional olive oil, then distribute caramelized onions, flaky sea salt, fresh rosemary, and black pepper evenly across the top.
10 - Bake for 25 to 30 minutes until the focaccia achieves a golden-brown color with crispy edges.
11 - Allow the focaccia to cool briefly before slicing and serving warm.

# Expert Advice:

01 -
  • The overnight cold rise in the fridge actually deepens the sourdough flavor, making it taste more complex without extra effort.
  • Caramelized onions are forgiving and rewarding—they transform from sharp and raw into sweet, silky magic, and your kitchen smells incredible while they cook.
  • One pan means minimal cleanup, and the focaccia stays fresh and soft for days if you store it properly.
02 -
  • Your starter's activity level matters more than the time on the clock—if it hasn't doubled after 6-8 hours, give it more time rather than rushing; a sluggish starter means sluggish dough.
  • Dimpling the cold dough straight from the fridge often leads to tearing because it's not fully relaxed; that room temperature hour is worth protecting because it prevents frustration and keeps those air pockets intact.
  • Caramelizing onions is genuinely about patience, not heat—high temperature browns them too fast on the outside while the inside stays raw; medium-low heat transforms them into something almost sweet, and stirring occasionally prevents any burnt edges.
03 -
  • If your sourdough starter is sluggish or cool, place the dough in a slightly warm spot (like on top of the refrigerator or in a turned-off oven with the light on) to speed things up—temperature control is half the battle with sourdough.
  • Extra caramelized onions freeze beautifully in an airtight container for up to three months; thaw and use them on pizza, in soups, or as a side dish anytime you want that deep, sweet onion flavor without the wait.
  • Focaccia is best eaten the day it's made, but it keeps well for 2-3 days wrapped in a towel or bag; reheat gently in a toaster oven to restore crispness.
Go back