01 -
Combine sourdough starter, sugar, water, and bread flour in a large mixing bowl until a shaggy dough forms. Cover and rest in a warm place for 1 hour.
02 -
Add salt and olive oil to the dough. Mix thoroughly by folding and pinching until fully incorporated.
03 -
Transfer dough to a covered container and let rise in a warm spot for approximately 1.5 hours, performing stretch and fold techniques every 30 minutes to develop gluten and shape into a rough square.
04 -
Place dough on a well-oiled baking sheet or parchment-lined pan. Let rest at room temperature in a warm area for 3 to 4 hours until bubbly and naturally spread out. Alternatively, refrigerate covered overnight up to 3 days and bake from cold.
05 -
Preheat oven to 450°F (232°C) and place a baking stone or steel in the center rack if available.
06 -
Press fingertips repeatedly into dough to create deep dimples. Drizzle olive oil generously over the surface, sprinkle with coarse salt and rosemary.
07 -
Bake directly on the stone or baking sheet for approximately 20 minutes until golden brown and bottom is crisp. If not using stone or steel, bake in the lower third of the oven to promote crispness.
08 -
Remove from oven and drizzle additional olive oil over the hot focaccia before slicing and serving.