Combine all ingredients except for the butter in a large mixing bowl (if using a bread maker, add into bread maker pan and set to "dough" feature).
Turn onto a floured board. Knead until a sticky dough ball is formed, adding additional flour as necessary.
Place dough ball in an oiled mixing bowl and cover with plastic wrap. All to rise for 2 hours. You can also put the dough in the fridge overnight (8-24 hours) for a long, slow fermentation. Either way, you'll want to see it double in size before you use it.
Grease a rimmed baking sheet. Punch down dough and turn into baking sheet, evenly pressing dough to the sides of the sheet. If the dough pulls away, let it rest for few minutes before continuing.
Cover with plastic wrap and allow to rise in a draft-free area until doubled in size, about 1-2 hours. Warm kitchens may go faster; cool kitchens may take longer, even up to 4 hours.
Preheat oven to 450° F (232° C). Gently dimple the top of the dough with the tips of your fingers.
Drizzle with olive oil and sprinkle with coarse sea salt.
Bake for 20-25 minutes or until golden brown. Cool in pan before turning onto rack. Melt the butter and brush on the top of the foccacia if desired. Slice and serve warm.
ENJOY!
Notes
Use your starter when it's recently been fed (today or the past 24 hours) and it's active and bubbly.
Experiment with other toppings! Try chopped olives, sliced bell peppers or tomatoes, red pepper flakes, sliced jalapeños, and any combination of shredded cheese.