Mix warm water, yeast, and sugar in a bowl.
Let it sit for 10 minutes until foamy.
In a big bowl, add flour and salt.
Pour in yeast mix and olive oil.
Stir with spoon until dough forms.
Knead dough on a floured surface for 8 minutes.
Put dough in oiled bowl and cover with towel.
Let it rise for 1 hour until double.
Heat oven to 400°F (200°C).
Place parchment paper on baking sheet.
Spread dough evenly on the sheet.
Press fingers to make small holes.
Brush dough with olive oil.
Add rosemary and coarse sea salt.
Bake for 20–25 minutes until golden brown.
Cool a little before cutting and serving.