Combine the flour, sugar, yeast and water in a bowl and let sit for about 15 minutes (the longer you let it sit, the more the yeast will take effect and the airier the bread will turn out).
Mix the ingredients together with a spoon until the dough comes together, then transfer to a floured surface and knead by hand until it's smooth - about 5-10 minutes. Work more flour into your dough if it's still sticking to your fingers.
Form a ball out of the dough and place in a well-oiled bowl and cover with plastic wrap. Let it sit for 1-2 hours (you want your dough to double in size).
If you're adding caramelized onions, you can make them while your dough is rising - it will take about 40-50 minutes.
Preheat your oven to 450 F. While preheating, clean and roughly chop the rosemary.
Spread the dough into an oiled pan (jelly roll pans work well since they have high edges) and dimple the surface with your fingers – you want this to look rustic.
Brush the focaccia dough with (more!!!) olive oil, sprinkle with salt. This is where you would add any toppings like onions, rosemary, olives, garlic, sun dried tomatoes... the list goes on!
Put in the oven and bake until golden brown – about 20-25 minutes.
Let cool, slice and enjoy!!!
Recipe by Ahu Eats at https://www.ahueats.com/2014/06/recipe-focaccia-bread.html