In the bowl of a stand mixer fitted with the dough hook, pour water and sugar. Sprinkle yeast on top of water and give it a quick mix. Let stand for 5-10 minutes until yeast starts to foam.
With the mixer on low, slowly add flour, salt and olive oil. Mix dough for about 5 minutes until dough is smooth and pulls away from the side. If the dough is still sticky, add 1/4 C more flour.
Place dough in a large bowl coated with nonstick spray or olive oil. Cover with a damp towel and set in a warm place until doubled in size, 45-60 minutes. (If it's a cold day, I turn my oven on to 150 degrees F, then turn off once it reaches temp and place the bowl in the oven.)
Preheat oven to 400 degrees F. Turn out dough onto a lightly floured surface. Roll out dough into circle or rectangle until about 1/2" thick. Cover with damp towel and allow to rise for another 20 minutes.
While dough is rising, thinly slice red onion and shred the parmesan cheese.
Transfer dough to a large baking sheet or baking dish with sides. Using your fingers, poke deep holes all over dough.
Now it's time for toppings! Start by drizzling 1-2 Tbsp olive oil evenly on top. Evenly place sliced red onions on top. Sprinkle parmesan and salt all over.
Bake for 25 minutes or until slightly golden.
This is such an easy and delicious focaccia bread to go with anything!