Seared Tuna Sandwich With Balsamic Onions

• 2 teaspoons butter
• 2 cups vertically sliced onion
• 1 1/2 tablespoons balsamic vinegar
• 1/4 teaspoon dried thyme
• 1 tablespoon all-purpose flour
• 1/2 teaspoon salt
• 1/4 teaspoon garlic powder
• 1/4 teaspoon black pepper
• 4 (6-ounce) tuna steaks (about1/2 inch thick)
• Cooking spray
• 4 teaspoons Dijon mustard
• 4 (2-ounce) whole wheat hamburger buns
• 4 curly leaf lettuce leaves
• 4 (1/4-inch-thick) slices tomato

1. Melt butter in a medium skillet over medium-high heat. Add onion; saute 5 minutes. Stir in vinegar and thyme; cover and cook 5 minutes, stirring occasionally.
2. While onion cooks, combine flour, salt, garlic powder, and pepper in a shallow dish. Dredge fish in flour mixture. Heat a large nonstick skillet coated with cooking spray over medium-high heat. Add fish; cook 3 minutes on each side or until desired degree of doneness.
3. Spread 1 teaspoon mustard over top half of each bun. Layer 1 lettuce leaf, 1 fish steak, 1 tomato slice, and 1/4 cup onion mixture on bottom half of each bun. Top with top halves of buns.

butter, onion, balsamic vinegar, thyme, flour, salt, garlic, black pepper, tuna, cooking spray, mustard, whole wheat hamburger buns, curly leaf, tomato

Taken from www.myrecipes.com/recipe/seared-tuna-sandwich-with-balsamic-onions (may not work)