Mix flour and salt together in a bowl; make a well in the centre and add yeast and sugar. Pour in warm water and add 1 tablespoon oil; knead until dough is soft and elastic.
Lightly oil a clean bowl; add dough and turn to coat with oil. Cover with clingfilm and leave to rise in a warm place.
Heat 2 tablespoons oil in a pan over medium heat; stir in onions and cook until soft. Add garlic and cook for 1 minute; stir in aubergines, courgettes, tomatoes and tomato puree. Add 3 or 4 tablespoons water and season to taste with salt and pepper; simmer for 30 to 40 minutes until thick.
Preheat oven to 220 C / Gas 7.
Knock back dough and divide into 2 parts. Knead each into a disc about 25cm (10 in) in diameter and place on an oiled baking tray. Brush dough lightly with oil and spoon ratatouille on top; add crumbled feta cheese and herbs.
Bake pizzas for about 15 minutes in preheated oven until bases are crisp and cheese is golden brown.