Preheat the oven to 400 degrees. In a saute pan, heat the olive oil. Add the chorizo and render for 2 to 3 minutes. Add the onions, shallots, garlic and peppers. Saute the mixture until the vegetables are light in color, about 2 minutes. Remove from the heat and turn into a mixing bowl. Season with salt, cayenne and parsley. Stir in the clams and creole mustard. Fold in enough bread crumbs to bind the mixture. Pack the mixture into each shell and tie with the butcher's twine. Place on a baking sheet and bake for 8 to 10 minutes, or until the stuffing is cooked through. Remove from the oven and place the untied clams on a platter. Drizzle the butter sauce over the clams. Place a small bundle of the leeks in the center of each clam. Garnish with red peppers, parsley and Essence.