Cooking Matters: Modern Tuna Casserole

Ingredients: • 3 tablespoons butter, divided • 4 medium carrots, chopped • 1 medium onion, chopped • 1 medium sweet red pepper, chopped  • 1 cup sliced baby portobello mushroom • 2 cans (5 ounces each) albacore white tuna in water, drained a ...