Tuna Melts with Horseradish Mayonnaise

Ingredients

• 2 teaspoons apple cider vinegar 
• 0.3 cup celery finely chopped
• 2 tablespoons parsley fresh finely chopped
• 8 slices havarti cheese thin
• 1 tablespoon horseradish prepared
• 4 servings kosher salt and pepper freshly ground
• 6 tablespoons mayonnaise 
• 4 large slices cocktail rye bread lightly toasted
• 2  scallions finely chopped
• 12 ounce solid tuna white drained canned
• 2  tomatoes cut into 8 slices
• 1 tablespoon whole-grain mustard 

Equipment

• bowl
• baking sheet
• oven

Directions

1. Position a rack in the upper third of the oven and preheat to 475 degrees F.
2. Combine 4 tablespoons mayonnaise, the tuna, celery, scallions, parsley and vinegar in a large bowl and mix well. Season with salt and pepper.
3. Combine the remaining 2 tablespoons mayonnaise with the mustard and horseradish in a small bowl; spread on the bread slices and arrange on a baking sheet. Mound the tuna mixture on top and pat it into an even layer. Top each with 1 cheese slice, tearing it as needed to cover the tuna mixture.
4. Season the tomato slices with salt; place 2 slices on top of each sandwich, then top each with another cheese slice.
5. Bake until the cheese melts, 5 to 7 minutes.
6. Serve with dill pickles.