Onion Focaccia

Why I Love This Recipe
This a a nice recipe I like to make on week-ends or when I have a bit more time. It is easy but requires a few steps and time to let the dough rise.
Ingredients You'll Need
DOUGH
2 tsp active dry yeast
1/4 cup lukewarm water
1 tsp sugar
1 tsp salt
4 cups all-purpose flour, plus extra for dusting
2 Tbsp of oil
Up to 1 1/2 cups lukewarm water
A little sunflower oil, for greasing
FOCACCIA
5 tbsp olive oil
2 large onions (red or yellow), sliced
handful rosemary sprigs (or dried rosemary)
1 tsp sea salt flakes, or to taste
Directions
DOUGH
1. In a small bowl, mix the active dry yeast, the 1/4 cup of lukewarm water, and sugar. Set aside for 10-15 minutes to let the yeast rise.
2. Make the dough by mixing the flour and salt into a large bowl, and making a well/hole in the middle. Pour in the yeast mixture from step 1, the oil, and most of the 1 1/2 cups of water. Using your fingers or a wooden spoon, mix the flour and water together until combined to a slightly wet, pillowy, workable dough - add a splash more water if necessary.
3. Place the dough onto a lightly floured surface and knead for at least 10 min until smooth and elastic. This can also be done in a tabletop mixer with a dough hook. Place the dough in a clean oiled bowl, cover with a clean towel (making sure the towel does not touch the dough) and leave to rise until doubled in size, approx. 25-30 min.
4. When the dough has risen, knock it back and stretch it to fit an oiled 25 x 35cm baking sheet. Leave the dough to rise for about 20 mins.
5. Heat oven to 200C. Spread the onions over the dough and scatter with the rosemary. Press your fingers into the dough to make dimples, drizzle the remaining oil over and scatter over the salt, then bake for 30 min until golden. Leave to cool, then serve cut or torn into squares.