Heat 1 tablespoon of the oil, over high heat. Saute the onions, green onions, celery, red peppers, shallots, and garlic, for 1 to 2 minutes. Add the crawfish tails, stock, bread crumbs, and 1 teaspoon of Essence and cook for 2 minutes. Remove from heat and allow to cool for at least 15 minutes. Using a small sharp knife, cut a slit about 2 inches long into the side of each steak and cut about 2 inches in to make a pocket. Season the meat with the remaining Essence inside and out of the pocket. Stand the steaks of their uncut edges and open the pockets. Using a spoon, fill each pocket with 1/4 cup of the stuffing. Heat the remaining 1 tablespoon oil in a saute pan over high heat. When the pan begins to smoke, add the filets and saute for 3 to 4 minutes on each side for medium rare.