Peel and wash the potatoes. Finely dice 1 potato. Peel, wash and finely dice the carrots. Clean, wash and also dice the leek. Cook diced vegetables in boiling salted water for 3 minutes, drain. Mix mustard and vinegar.
Season to taste with salt, pepper and sugar. Add 2 tablespoons of oil. Stir in the vegetables. Wash the turkey meat, dab dry, tap flatter. Season with pepper and roll up with 1/2 slice of bacon and pin. Heat 2-3 tablespoons of oil in a frying pan. Fry the rolls in it until golden brown all around, season with a little salt and fry for about 5 minutes. Sprinkle the marinade on the rolls and let them simmer covered. Grate the remaining potatoes. Mix with the egg, season with salt and pepper. Heat 3 tablespoons of oil and add the potato mixture spoon by spoon to the remaining hot oil.
Heat 2-3 tablespoons of oil in a frying pan. Fry the rolls in it until golden brown all around, season with a little salt and fry for about 5 minutes. Sprinkle the marinade on the rolls and let them simmer covered. Grate the remaining potatoes. Mix with the egg, season with salt and pepper. Heat 3 tablespoons of oil and add the potato mixture spoon by spoon to the remaining hot oil. Fry on each side for 2-3 minutes until crispy (makes about 16 pieces). Place 1 roll on each and serve garnished with chervil