1 Peel and chop the onions with their stalks. Brown them without colouring, 10mn in a frying pan oiled with butter.
2 Preheat the oven to 180°c (th6). Cover the baking sheet with baking paper and spread the dough on it. Prick it with a fork
3 Arrange the onions on the dough. Wash, dry and then cut the tomatoes into rings, spread them over the onions.
4 Thinly slice and sprinkle the thyme, pour a drizzle of olive oil over the tart, season generously with salt and pepper. Bake for about 30 minutes.