In a deep bowl, mix the flour, sugar, salt and butter. Gradually add the cold water and knead a smooth dough. Cover the dough with a foil for fresh food and leave in the fridge for 30 minutes. From the dough on baking paper, roll out a crust in a circular shape with a thickness of 1 cm. In the middle, apply the previously prepared sour cream filling mixed with dill, garlic, yellow cheese and olive oil. The filling is carefully applied with a spoon, leaving 2 cm from the ends. The tomato circles are arranged on the filling. The ends of the crust are folded inwards and coated with a beaten egg. If desired, sea salt can be sprinkled on top. The galette prepared in this way is baked for 30 minutes at a temperature of 200° C.