Dice white bread and then grind finely in the universal chopper. Clean, wash and very finely chop the leek. Grate cheese finely. Wash parsley, shake dry and chop finely, except for a few leaves for garnishing. Separate eggs
Mix 125 g white bread, cheese, leek, parsley, except for 1 tbsp for garnishing, mustard powder, 1 tsp salt and pepper in a bowl. Add 6 egg yolks and 4-5 tablespoons of water, knead well with your hands (it sticks a little). Form approx. 16 croquettes (approx. 6 cm long, approx. 1.5 cm Ø). Let rest for about 15 minutes
In the meantime clean and wash the salad, drain well and pluck into bite-sized pieces. Wash, clean and slice the tomatoes. Wash and peel the cucumber, quarter it lengthwise and cut it into pieces
For the vinaigrette, mix vinegar, salt, pepper and sugar. Fold in 3 tablespoons of oil. Mix lettuce, tomatoes and cucumbers, pour vinaigrette over
Whisk the egg white in a deep plate with a fork. Put 125 g breadcrumbs on another plate. Heat oil in portions in a large frying pan. Turn cheese croquettes first in egg white, then in bread crumbs. Fry for about 3 minutes until golden brown. Remove from the pan
Arrange cheese croquettes and salad on plates, sprinkle with parsley and garnish