Cook the mussels, over a high heat, until they open. Remove the mussels from their shells and put 10 to a ramekin. Mix all the ingredients of the garnish together with the butter and lemon juice. Add salt and pepper. Preheat the oven to 450F. Place a teaspoon of the garnish on the mussels. Just before serving this appetizer, reheat in the oven for about 5 minutes. As soon as you see the mussels start to boil, serve them immediately with toast.