Ingredients:

  • 2 medium yellow onions, thinly sliced (approx. 300g / 10.5 oz)
  • 2 tablespoons olive oil (30 ml)
  • 1 tablespoon butter (15g / 0.5 oz), unsalted
  • 1 tablespoon brown sugar (15g / 0.5 oz)
  • 1/4 teaspoon salt (1.5g / 0.05 oz)
  • 1/4 cup dry white wine or chicken broth (60 ml / 2 fl oz) optional
  • 2 cans (5 oz/142g each) tuna in olive oil, drained well (approx. 284g / 10 oz)
  • 1/4 cup mayonnaise (60g / 2 oz)
  • 2 tablespoons finely chopped celery (30g / 1 oz)
  • 1 tablespoon finely chopped red onion (15g / 0.5 oz)
  • 1 tablespoon lemon juice (15 ml / 0.5 fl oz)
  • 1/2 teaspoon Dijon mustard (3g / 0.1 oz)
  • 1/4 teaspoon black pepper (1.5g / 0.05 oz)
  • Pinch of red pepper flakes (optional)
  • 1/4 cup mayonnaise (60g / 2 oz)
  • 1 clove garlic, minced (3g / 0.1 oz)
  • 1 teaspoon lemon zest (3g / 0.1 oz)
  • 1/2 teaspoon lemon juice (2.5 ml / 0.1 fl oz)
  • 4 slices sourdough bread
  • 4 ounces (115g / 4 oz) Gruyère cheese, grated
  • 2 tablespoons butter, softened (30g / 1 oz)

Instructions:

  1. Sauté onions in olive oil and butter over medium heat until softened. Add sugar and salt, and cook, stirring occasionally, until golden brown and caramelized (about 15-20 minutes). Deglaze with white wine or broth (optional) during the last few minutes. Set aside.
  2. Whisk together mayonnaise, minced garlic, lemon zest, and lemon juice in a small bowl for lemon aioli.
  3. Combine drained tuna, mayonnaise, celery, red onion, lemon juice, Dijon mustard, pepper, and red pepper flakes (if using) in a medium bowl. Mix gently for the tuna salad.
  4. Spread softened butter on one side of each slice of bread. Spread the lemon aioli on the other side of each slice of bread.
  5. On two slices of bread (aioli-side up), pile half of the grated Gruyère, followed by half of the tuna salad, and then half of the caramelized onions. Top with the remaining Gruyère.
  6. Place the remaining slices of bread (aioli-side down) on top. Grill the sandwiches in a preheated griddle pan or frying pan over medium heat, pressing down gently with a spatula, until golden brown and the cheese is melted and gooey (about 3-4 minutes per side).
  7. Cut in half and serve immediately. These tuna recipes are delicious