Season the fillets with Essence. In a large saute pan, melt the butter. Stir in the flour, stirring constantly for 5 to 6 minutes for a medium brown roux. Add the onions, celery, and peppers. Season with salt, pepper, and cayenne. Cook for 6 to 7 minutes, stirring constantly, or until the vegetables are wilted. Add the water and stir until the mixture thickens, 6 to 7 minutes. Add the lemon juice and lay the trout in the pan and baste with the sauce. Cover and cook for 6 to 7 minutes or until the fish flakes easily with a fork. Add the parsley and remove from the heat. Serve over white rice.