Heat up a couple of tablespoons of olive oil in a large saucepan and start softening the onions for about 5 minutes until they turn translucent . Add the thyme and the garlic, give it stir and add the chopped courgettes, aubergine and peppers. Season with salt and pepper and cook for a few minutes. Stir in the tomato puree and just after the chopped tomatoes.
Cook everything with the lid on for 20-30 minutes stirring occasionally. Once the vegetables turn tender season again with salt and pepper and serve still warm.