For the ham and tomato quiche, first prepare the dough. For the dough, mix flour, butter, water and salt to a kneaded dough, wrap in plastic wrap and let rest in the refrigerator for about 30 minutes.
During this time you can already preheat the oven to 200 °C. Line the bottom of a springform pan (26 diam.) with baking paper and grease the sides.
Take the dough out of the refrigerator and roll it out on a floured work surface and place it in the prepared pan, raising a rim of about 3 cm and pricking it several times with a fork.
For the topping, spread ham and tomato halves (cut side up) on the bottom. Dice onion finely. Mix all ingredients including onion in a bowl until creamy.
Pour the mixture over the tomatoes and ham and bake in the oven. Baking time: 200 °C top/bottom heat, approx. 45 min. depending on the desired browning.