Wash potatoes, boil in their jackets in salted water for about 20 minutes. Cut broccoli into pieces and florets and blanch for 10 minutes in salted water, drain, dry. Potatoes also drain, clean potatoes when warm. Rinse shrimps. Peel shallots and chop. Melt butter and pass shallots until transparent, sprinkle with flour, stir, pour the broth and cream, add the vermouth, salt and pepper. Put shrimps in cooked sauce. Rinse salmon, drizzle with lemon juice, salt and pepper. Cut potatoes into slices and put together with the broccoli in one large greased form. Top with salmon and shrimps with sauce. Bake for about 20 minutes in the oven at 200 degrees Celsius. Wash dill, dry, chop and sprinkle with gratin before serving.