Mix the water with yeast and olive oil. Mix the flour and salt, add the yeastwater and knead until you have s supple dough. Grease a bowl with olive oil, transfer dough, cover and let is rest until it has doubled in size.
Grease a baking tray. Carefully let the dough drop onto the tray, it won't stick to the bowl because of the oil. Stretch the dough so it covers the entire baking tray, cover and let is rise for another 30 minutes.
Preheat the oven to 200 degrees celcius.
Cut strands of the courgette, half the cherry tomatoes and cut the onions in rings. Form dimples by using your fingers of knuckles and decorate your focaccia with the veggies, or not if you want a regular focaccia. Generously sprinkle olive oil and sesalt onto your dough. Bake until golden brown, about 20-25 minutes.
Let it cool off a bit before serving.