In the meantime, get ready your onions: Warmth a big sauté pan about medium warmth. After very hot, include 2 tablespoons olive oil. After the oil is heated, increase the onions and 1 teaspoon kosher salt. Cook onions, stirring every minute or two, till a medium brown, almost caramel coloured, about 25 minutes. [See Note at end.] Scrape onions on to a plate to interesting even though you finish the bread.
Complete 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 top of the dough with a different tablespoon of olive oil and use your fingers to dimple the dough, flattening it out. It’s ok if it does not achieve the edges. Enable the dimpled dough relaxation at room temperature for 15 minutes and warmth your oven to 425°F. Right after 15 minutes, dimple the dough only wherever desired a tiny further into the corners. Permit rest for a remaining 15 minutes in advance of scattering the top rated with onions, poppy seeds, and a several pinches of salt.
Bake the focaccia: For 25 minutes, right until deeply golden brown at the edges and throughout the top. When it bakes, you can prepare any toppings you’d like to serve it with, these as cream cheese or butter, lox, thinly sliced tomatoes, cucumbers, onions, or capers.
To serve: Loosen the focaccia if it is caught in any place and slide it into a slicing board. Lower into 12 squares, employing a sharp knife to get by way of the onions on major devoid of pulling them off, and replacing any that scatter. Consume correct absent.
Do ahead: Focaccia retains at home temperature for 1 to 2 times. Reheat on a baking sheet at 350°F for 10 to 12 minutes.
Take note: These are not caramelized onions we do not require 60 to 90 minutes above small heat with continual stirring. That is not how any ancestor of mine cooked onions. I’m deliberately making use of a increased heat for a lot more promptly developed flavor. If they are not finding up colour by 20 minutes, bump up the warmth slightly. If they’re coloring way too quickly to make it to 20 to 25 minutes, minimize the warmth. We want to stopping shy of a dark bronzed colour, as the onions will finish in the oven and we don’t want them to melt away.