Boil potatoes al dente, drain and allow to cool down.
Soak toast in water.
Mix well soup, 1 tbsp. mustard, 3 tbsp. oil, vinegar, salt and pepper. Cut potatoes into thick slices and mix with the marinade.
Squash toast and knead together with mince, onion, 1 tsp. mustard and egg. Season with salt and pepper. Form small balls and fry for 8-10 minutes all around.
Remove and set aside.
Wash the vegetables. Remove the dark green and cut fresh onions into rings, radishes into slices.
Wash frisée and cut into bite-size pieces.
Mix vegetables and salad with the potatoes and serve with the meatballs.