Make the dough: Mix the water, instant yeast, honey and sourdough discard in a large bowl until no traces of discard remains.
452 grams water, 7 grams instant yeast, 42 grams honey, 170 grams sourdough discard
Fold in the bread flour, whole wheat flour and salt. Mix with a wooden spoon or your hands until all of the flour is hydrated.
540 grams bread flour, 90 grams whole wheat flour, 12 grams salt
Knead the olive oil into the dough until it is absorbed. It will gradually feel less greasy as it absorbs the oil.
56 grams olive oil
Cover the bowl with plastic wrap and let the dough rest in a warm place for 15 minutes.
Stretch and fold: After the 15 minute rest period, complete 1 set of stretch and folds.
To complete a stretch and fold, with the dough inside your bowl, pick up the side of the dough closest to you using your fingertips. Stretch the dough out as much as you can without it tearing and fold it over itself. Turn the bowl 90 degrees and repeat 3 more times.
Cover the bowl with plastic wrap. Set it in a warm place and let the dough rest for 15 minutes.
Complete 1 more set of stretch and folds. Cover the bowl with plastic wrap.
First rise: Let the dough rise at room temperature until doubled in volume. The dough should double in volume and appear bubbly, about 30 to 45 minutes.
Prep: Line two 9 by 13 baking sheets aluminum foil or parchment paper. Coat the bottom of the sheet pans with about 1 tablespoon of olive oil (14 grams). Preheat the oven to 425 F. (Coat bottom of the pan with 28 grams of olive oil if you're baking 1 large focaccia)
Second rise: Divide the dough into two portions. Transfer each portion of dough on the prepared pans. Cover the pans with plastic wrap and let the dough rest for 15 minutes.
After the rest period, stretch the dough out to the edges of the pan. Cover the dough once more and let it rise for another 20 minutes or until it looks bubbly.
Assemble and top: Working with one portion of dough at a time, pour about 1 tablespoon (14 grams) of olive oil over the dough. Spread the oil on the dough using the palm of your hand. Using your fingertips, dimple the dough all over until it looks completely flat.
7 grams flaky sea salt
Sprinkle sea salt and arrange toppings on the dough (if using). Repeat with the remaining portion of dough.
Bake: Transfer the baking sheets to the oven and bake for 25 to 30 minutes or until the focaccia looks golden brown.
Enjoy: Transfer the focaccias to a cooling rack. Let the bread cool for 10 minutes before slicing, more if you’re using it for a sandwich.
Store: This bread tastes the best the day it is baked, but will store well for up to 3 days in an airtight container at room temperature. Refrigerate leftover slices in an airtight container if you used toppings.