Wash the potatoes and cook them in water for 20-30 minutes. Stir the broth in 250 ml of hot water. Stir in mustard, oil and vinegar. Season the vinaigrette with salt and pepper. Drain the potatoes, rinse and peel off the peel. Cut into slices, mix with the vinaigrette and let the salad steep.
Spread the fish fingers on a baking tray lined with baking paper. Bake in a hot oven (225 ° C) for about 15 minutes, turning once.
Wash, clean and slice the tomatoes. Wash the rocket and pat dry. Fold both under the salad and season the salad to taste again.