For the mustard eggs, hard boil eggs, rinse, peel and cut in half lengthwise. Remove yolks and mash with a fork and cream with butter.
Stir in mustard and pipe into egg halves with a piping bag. Wash tomato, cut into thin strips and garnish eggs with it.
Arrange the mustard eggs on lettuce leaves.
Preparation Tip:
If you want to make different looking mustard parties, you can also use other vegetables for garnish.