Boil the eggs hard in about 10 minutes, quench, peel and finely chop them. Cut bacon into small cubes. Peel and finely chop the onion. Heat oil and leave the bacon in it until crispy. Add the onion, fry it and let it cool down a bit. Add vinegar and season to taste with salt, pepper and sugar.
Fold in the egg cubes. Wash and clean the cucumber and cut it into thick sticks. Clean, wash and drain the salad. Arrange lettuce and cucumber on plates. Spread the egg-bacon vinaigrette over it