Tuna Melt - Sandwich Recipe

Preheat oven to 400°F (200°C). Cut the top off each garlic bulb to expose the cloves. Place bulbs on a sheet of foil, drizzle with 2 Tbsp olive oil, sprinkle 1/4 tsp salt, wrap tightly and roast 35–40 minutes until cloves are soft and caramelized. Let cool, then squeeze roasted cloves into a small bowl and mash into a smooth paste. Set aside.

Preheat (can be done simultaneously with garlic) oven to 400°F (200°C). Arrange halved tomatoes cut-side up on a baking sheet. Drizzle with 1 Tbsp olive oil and 1 tsp balsamic vinegar, season with 1/4 tsp salt and 1/8 tsp pepper. Roast 20–25 minutes until edges are slightly caramelized and juices concentrate. Remove and let cool slightly.

In a wide skillet over medium-low heat, melt 1 Tbsp butter with 1 tsp olive oil. Add the thinly sliced onions and 1/4 tsp salt. Cook slowly, stirring occasionally, for 25–30 minutes until deep golden and soft. If onions are drying, add a tablespoon of water. Stir in 1/2 tsp brown sugar in the last 5 minutes to encourage caramelization if desired. Remove from heat and keep warm.

Flake the drained tuna into a mixing bowl with a fork to break up large pieces.

Add 3 Tbsp mayonnaise, 1 Tbsp Greek yogurt, and 1 tsp Dijon mustard. Stir until combined and creamy.

Fold in 1/2 cup finely diced celery, 1/4 cup finely diced red onion, 1 Tbsp chopped capers, 1 Tbsp lemon juice and 2 Tbsp chopped parsley. Season with 1/2 tsp salt and 1/4 tsp black pepper. Taste and adjust seasoning. If you prefer a creamier salad, add up to 1 more tablespoon mayo.

Prepare bread

Butter one side of each bread slice lightly (about 2 Tbsp divided). Alternatively, brush with 1 tsp olive oil for a lighter option.

Build sandwiches

Place 4 bread slices buttered side down. Spread about 1/2 tsp roasted garlic paste onto each slice. Divide the tuna salad evenly among the 4 slices (about 3 oz tuna salad per sandwich base). Top the tuna with equal portions of roasted tomatoes (2 halves per sandwich), 2 oz sliced fresh mozzarella per sandwich, and a generous spoonful of caramelized onions. Add a lettuce leaf on top of the cheese for freshness. Optionally sprinkle a pinch (about 1/16–1/8 tsp) of red pepper flakes for heat.

Close sandwiches with the remaining bread slices, butter side up. Heat a skillet or griddle over medium heat. Toast sandwiches 3–4 minutes per side, pressing lightly with a spatula, until bread is golden brown and mozzarella is melted. If cheese needs more time to melt, cover the pan with a lid for 1–2 minutes.

Remove sandwiches, let rest 1 minute, then cut each sandwich in half and serve warm.