In the meantime, prepare your onions: Warmth a big sauté pan more than medium heat. At the time very hot, insert 2 tablespoons olive oil. The moment the oil is heated, include the onions and 1 teaspoon kosher salt. Cook onions, stirring every moment or two, till a medium brown, just about caramel colored, about 25 minutes. [See Note at end.] Scrape onions on to a plate to interesting whilst you end the bread.
Finish the focaccia: When the dough is doubled, pour 2 tablespoons olive oil into a 9×13 cake pan. Do not deflate your dough, just scrape it into the oiled pan. Drizzle the prime of the dough with another tablespoon of olive oil and use your fingers to dimple the dough, flattening it out. It’s ok if it doesn’t reach the edges. Let the dimpled dough rest at place temperature for 15 minutes and heat your oven to 425°F. Just after 15 minutes, dimple the dough only where needed a little more into the corners. Permit relaxation for a final 15 minutes ahead of scattering the leading with onions, poppy seeds, and a couple pinches of salt.
Bake the focaccia: For 25 minutes, until eventually deeply golden brown at the edges and across the top. Though it bakes, you can get ready any toppings you’d like to provide it with, such as product cheese or butter, lox, thinly sliced tomatoes, cucumbers, onions, or capers.
To serve: Loosen the focaccia if it is stuck in any place and slide it into a reducing board. Cut into 12 squares, utilizing a sharp knife to get by means of the onions on top rated devoid of pulling them off, and changing any that scatter. Take in right away.
Do ahead: Focaccia retains at room temperature for 1 to 2 days. Reheat on a baking sheet at 350°F for 10 to 12 minutes.
Notice: These are not caramelized onions we do not want 60 to 90 minutes in excess of small warmth with regular stirring. That is not how any ancestor of mine cooked onions. I’m intentionally making use of a bigger heat for far more quickly designed flavor. If they are not finding up color by 20 minutes, bump up the warmth a little. If they are coloring way too rapidly to make it to 20 to 25 minutes, lessen the heat. We want to stopping shy of a dark bronzed shade, as the onions will end in the oven and we don’t want them to burn off.