Wash the potatoes and cook in boiling water for about 20 minutes. Drain potatoes, quench, peel and let cool. Wash and halve the tomatoes. Clean, wash and drain the rocket.
Halve the avocado and remove the stone. Peel avocado, cut flesh into pieces and sprinkle with 1 tablespoon lemon juice. Mix 5 tablespoons lemon juice, salt, pepper, mustard and sugar. Add 4 tablespoons of oil.
Slice the potatoes, add the tomatoes and avocado. Pour marinade over it. Wash the salmon, dab dry and cut into pieces. Heat 2 tablespoons of oil in a pan. Fry the salmon for about 3 minutes while turning.
Season with salt and pepper. Season potato salad again. Carefully fold in salmon and rocket. Arrange potato salad on a plate, grind pepper over it.