1/2 cup vegetable oil 1/4 cup white wine vinegar 1 teaspoon salt 1/4 teaspoon ground black pepper 1/4 teaspoon dry mustard 1/8 teaspoon cayenne pepper 1 1/2 pounds bass fillets, cut into 1-1/2-inch cubes 16 mushrooms, cleaned 3 onions, peeled and cut into 1-1/2-inch cubes 3 medium tomatoes, cored and cut into 1-1/2-inch cubes 2 green bell peppers, seeded and cut into 1-1/2-inch pieces 

Combine oil, vinegar, salt, pepper, dry mustard and cayenne pepper in a medium bowl; add bass and marinate in the refrigerator for 1 hour.Preheat grill. Using metal skewers or wood skewers that have been soaked in water, alternate fish, mushrooms, onions, tomatoes and green peppers. Brush with remaining marinade. Place skewers on a grill 4 inches above the hot coals. Cook only until edges of fish begin to curl, turning once, about 8 minutes. Serve hot.Serves 6.