Heat up skillet and add olive oil.

Cut up onions and muenster cheese finely and throw into the skillet. Stir until cheese melts and forms a united mass with the onions.

Add thr eggs and stir untill scrambled all together with the onion and cheese. Cook untill almost well done.

Cut the onion bun in half and toast.

Take a slice of mozzarella and add on top of the eggs. Then slowly remove and top with a slice of tomato and put into the toasted bun.