Ingredients:

Instructions:

  1. In the mixing bowl, flake the drained tuna thoroughly.
  2. Add the mayonnaise, diced celery, minced red onion, English mustard, lemon juice, and parsley to the tuna. Mix gently until just combined—do not overmix.
  3. Taste the mixture and season generously with salt and pepper.
  4. Lay out the four slices of bread. Spread a thin layer of the tuna mixture evenly on two slices. Top each with two slices of cheese, ensuring coverage extends near the edges. Place the remaining bread slices on top.
  5. Evenly spread the softened butter onto the outside of all four slices of bread.
  6. Heat the skillet over medium heat. Place the sandwiches in the skillet (buttered-side down). Cook for 3–4 minutes until the bottom is deeply golden brown and crisp.
  7. Carefully flip the sandwiches. Reduce the heat slightly to medium-low. Cover the pan briefly for 1–2 minutes to help the cheese melt through.
  8. Remove from the pan once both sides are golden and the cheese is gooey. Slice diagonally and serve immediately.