Preheat the oven to 200°C.
Melt 25g of butter in a saucepan and soften the shallots.
Boil the vermouth until reduced by two thirds, then add stock and reduce by two thirds again.
Simmer the cream until thickened, then stir in 50g chopped shrimp, 50g butter, tomatoes, parsley, and 100g whole shrimp.
Crush potatoes, mix with 25g butter and remaining shrimp, then fry until golden-brown.
Place lobster meat on a tray with 100g butter, cover with foil, and heat in the oven for 3 minutes.
Whisk mustard, vinegar, and oil together and toss with the salad vegetables.
Plate the potato hash, top with lobster, and pour over the shrimp sauce.