Season the fish with the rub.
Heat the butter in a large skillet over medium-high heat. Add the flour and, stirring constantly for 5 to 6 minutes, make a medium brown roux, the color of peanut butter.
Add the onions, celery, bell peppers, salt, cayenne, and black pepper. Stir briskly, coating the vegetables with the roux mixture and separating the onions rings. Continue stirring for 6 to 7 minutes, 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 right away.
Yield: 4 servings