In the meantime, put together your onions: Warmth a big sauté pan over medium warmth. As soon as sizzling, add 2 tablespoons olive oil. As soon as the oil is heated, add the onions and 1 teaspoon kosher salt. Prepare dinner onions, stirring each minute or two, till a medium brown, nearly caramel coloured, about 25 minutes. [See Note at end.] Scrape onions onto a plate to chill when you end the bread.
End the focaccia: When the dough is doubled, line a 9×13 cake pan with parchment paper and drizzle 2 tablespoons olive oil over it. Don’t deflate your dough, simply scrape it onto the oiled parchment. Drizzle the highest of the dough with one other tablespoon of olive oil and use your fingers to dimple the dough, flattening it out. It’s okay if it doesn’t attain the perimeters. Let the dimpled dough relaxation at room temperature for quarter-hour and warmth your oven to 425°F. After quarter-hour, dimple the dough solely the place wanted a bit of additional into the corners. Let relaxation for a remaining quarter-hour earlier than scattering the highest with onions, poppy seeds, and some pinches of salt.
Bake the focaccia: For 25 minutes, till deeply golden brown on the edges and throughout the highest. Whereas it bakes, you possibly can put together any toppings you’d prefer to serve it with, akin to cream cheese or butter, lox, thinly sliced tomatoes, cucumbers, onions, or capers.
To serve: Loosen the focaccia if it’s caught in anywhere and slide it right into a slicing board. Minimize into 12 squares, utilizing a pointy knife to get via the onions on prime with out pulling them off, and changing any that scatter. Eat immediately.
Do forward: 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 usually not caramelized onions; we don’t want 60 to 90 minutes over low warmth with fixed stirring. That isn’t how any ancestor of mine cooked onions. I’m deliberately utilizing a better warmth for extra rapidly developed taste. In the event that they’re not choosing up shade by 20 minutes, bump up the warmth barely. In the event that they’re coloring too quick to make it to twenty to 25 minutes, scale back the warmth. We wish to stopping shy of a darkish bronzed shade, because the onions will end within the oven and we don’t need them to burn.