Pickled Shallots 

1. In a small bowl, combine ½ cup red wine vinegar, 1 teaspoon granulated sugar, ½ teaspoon kosher salt, and 2 tablespoons hot water, stirring until dissolved.
2. Add 1 thinly sliced medium shallot, pressing down to ensure they are fully submerged. Let sit at least 20 minutes while preparing the rest of the recipe. The flavor improves with time, so these can also be made several days in advance.

Tuna Melts

1. Place an oven rack about 6 inches from the broiler and preheat the broiler.
2. In a medium bowl, whisk together 6 tablespoons mayonnaise, ⅓ cup sweet French dressing, ½ teaspoon lemon zest, 1 tablespoon fresh lemon juice, ¾ teaspoon kosher salt, ¼ teaspoon freshly ground black pepper, and ¼ teaspoon garlic powder until smooth.
3. Add ¼ cup finely chopped scallions, ¾ cup finely chopped celery, and 1 finely chopped small serrano chiles, and stir to combine.
4. Add 3 (5-ounce) cans chunk white albacore tuna, drained well, and gently fold with a fork, flaking just enough to combine. The tuna should be chunky, not shredded.
5. Taste the tuna salad. It should be sweet, savory, and have a noticeable but balanced heat, without being overly sweet. If needed, add more French dressing to boost sweetness, a pinch of salt to sharpen the flavors, or a small squeeze of lemon juice for brightness. If the serrano is mild, add more to taste.
6. Toast 4 slices of hearty white bread in a toaster and place them in a single layer on a sheet pan.
7. Divide the tuna salad evenly among the toast, spreading all the way to the edges. Top each slice with 1 slice American cheese.
8. Place under the broiler and cook for 1 to 2 minutes, rotating the pan as needed, until the cheese is fully melted, bubbling, and just starting to brown in spots. Watch constantly — this can go from perfect to burnt in under 30 seconds.
9. Remove from the oven and immediately top with desired amount of drained pickled shallot and a generous sprinkle of finely sliced chives. Let rest for 1 minute, then serve hot.