Wash the potatoes and cook in plenty of boiling water for about 20 minutes. Rinse under cold water, drain and peel. Cut potatoes in half. For the vinaigrette, whisk vinegar, salt, pepper, mustard and honey.
Add 4 tablespoons of oil drop by drop. Wash the dill, shake dry, pluck flags from the stems and cut finely. Stir into the vinaigrette. Mix potatoes and vinaigrette. Wash fish, dab dry, cut into large cubes and season with salt and pepper.
Put fish cubes on skewers. Heat 2 tablespoons of oil in a large frying pan and fry the fish skewers for about 5 minutes while turning. Wash and halve the tomatoes. Wash, clean and shake spinach dry.
Carefully fold the tomatoes and spinach into the marinated potatoes. Arrange salad and one fish skewer on each plate.