Wash the potatoes and cook in boiling water for about 20 minutes. Drain potatoes, quench, peel and press them through the potato press while still hot, let them cool down. Knead egg yolk and flour into the potato mixture.
Season with salt, pepper and nutmeg. Form potato dough into 3 squares (approx. 8 x 8 cm) on a floured work surface. Cut the cheese into 3 cubes and place them in the middle of the squares. Fold the dough into triangles.
Press the edges firmly, chill for about 5 minutes. Clean, wash and drain the salad. Wash tomatoes, possibly halve them. Peel and finely dice the shallot. Mix with vinegar, salt, pepper and sugar.
Add 1 tablespoon of oil. Mix the salad ingredients with the vinaigrette. Fry the slices in 1 tablespoon of hot oil for 2-3 minutes on each side until golden brown. Serve with salad.