Dice the onions very small, fry when they turn color, add the minced meat, fry until crumbly. In the meantime, cut the carrots into very small pieces or simply grate them. Fry these with the minced meat. Season everything vigorously with salt, pepper and paprika powder. Add half a tablespoon of tomato paste and stir in briefly. Add water until the tomato paste dissolves, it must not become liquid! Add a very small pinch of sugar.
Cut the mozzarella into small thin pieces and the tomatoes into slices. Now place tomato slices on the mozzarella pieces and season with salt and pepper. If you like, you can add a leaf of basil on top.
Roll out the puff pastry thinly and cut into squares. First put a good teaspoon of minced meat mixture on top (depending on the size of the squares), then place the mozzarella tomatoes on top. Then put the corners of the squares together towards the middle. Brush with egg or water. Then bake for about 15 minutes (shorter or longer depending on the stove).