Cut the cucumber into slices, cut the tomato into small pieces.
Heat the oil in a pan and add the egg. Fry at a low temperature until the egg white has set on the bottom, but the egg yolk is still liquid.
Turn off the stove, stir the egg a little, add the tomatoes and cucumber, season with salt and pepper and sprinkle with the cheese. Cover the pan and wait until the cheese has melted, if necessary turn on the stove again briefly.