Sift the flour and salt and place in food processor. Cut the butter into pieces and add. Mix in 1 min. To a crumbly dough. Run the processor and add the egg and water. Run until a cohesive dough. If necessary, add 1 tbsp cold water. Knead the dough briefly with your hands into a ball. Let rest in cling film for 30 min, in the refrigerator.
Preheat the oven to 180 ° C. Cut the tomatoes into thin slices.
Beat the remaining eggs with the sour cream. Crumble the goat cheese and stir into the egg mixture 2/3. Grate the yellow rind of the lemon and squeeze the fruit off. Stir in the zest and 3 tablespoons of juice into the egg mixture.
Dust the work surface and rolling pin with flour. Roll the dough into a round piece of diameter 32 cm. Grease the quiche dish with the butter. Line the mold with the dough. Prick the bottom. Divide the tomato, the egg mixture, and the rest of the cheese crumbles over the bottom. Bake in about 45 min. In the oven until golden brown.