1. Cook the eggs for 10 minutes in boiling water, then put them in cold water to stop the cooking process.
2. Make a mayonnaise with 1 egg yolk, 1 teaspoon of mustard, 1/4 liter of oil, and lemon juice (optional), or use store-bought mayonnaise. Add the lemon juice at the last moment.
3. Peel the eggs, cut them lengthwise, and separate the whites from the yolks.
4. In a shallow plate, crumble the yolks with a fork, mix half of these crumbled yolks with the mayonnaise, and reserve the rest.
5. Fill the half-whites with this mixture, then sprinkle each half-egg with the remaining crumbled yolks (which creates the "mimosa" effect!).
6. Arrange the eggs on lettuce leaves, put a little parsley and a black olive on each egg.
Serve chilled.