In 4-quart saucepan, melt 3 tablespoons butter over medium heat. Cook poblano chiles, onion and bell pepper in butter 8 to 10 minutes or until softened. Add garlic and 3 tablespoons flour; cook 2 minutes, stirring frequently. Add tomatoes, taco seasoning mix, 1/2 teaspoon salt and the pepper. Cook and stir 1 minute.