Lobster thermidor Serves: 1 Ingredients 1 450g-675g live lobster, or cooked for the sauce: 15g butter 1 shallot, finely chopped 60ml white wine 60ml fish or shellfish stock 75ml double cream ¼ tsp English mustard 1½tsp lemon juice, freshly squeezed 1tbsp flat leaf parsley, finely chopped 1tsp tarragon, finely chopped salt and freshly ground black pepper 40g grated Gruyere