• Remove the stems and seeds from the sweet mini peppers; finely chop the peppers.
• If using the jalapeño, remove the stem, ribs, and seeds; finely chop the jalapeño. Wash your hands after handling.

In a dry small sauce pot over medium-high heat, add the mustard seeds and toast, stirring constantly, until golden and popping, 1 to 2 minutes. Add the sweet mini peppers, quick-pickle brine, ½ cup [1 cup] water, and as much jalapeño as you like and season with salt and pepper. Bring to a boil, then reduce to a simmer and cook, stirring occasionally, until the peppers are just tender and the liquid has thickened, 7 to 10 minutes. Remove from the heat, cover, and let stand while you prepare the rest of the meal. 

• Set aside half the Italian cheese blend for the caprese salad. Divide the remaining half into 4 [8] portions for the sliders. 
• Cut a small corner from the protein packaging and drain off any excess liquid. Transfer to a plate; pat dry with a paper towel.

In a medium bowl, add your protein, season generously with salt and pepper, and mix gently until just combined. Using wet hands, form the mixture into 4 [8] equal portions and shape each into a ball. Using your thumb or the back of a spoon, make an indentation in the center of each ball and place 1 portion of the cheese blend into the indentation. Gently wrap the meat around the cheese, making sure it is completely covered. Form the balls into ½-inch-thick patties. 

In a large frying pan over medium-high heat, warm 1 tablespoon oil until hot but not smoking. Add the patties.

Beef-pork, beef, pork sausage, or plant-based meat: Cook, turning once, until browned and cooked to the desired doneness, 2 to 4 minutes per side. 

Chicken or turkey: Cook, turning once, until browned and cooked through, 4 to 6 minutes per side.

Transfer the sliders to a plate. Do not clean the pan. While the patties are cooking, prepare the salad.

• Cut away the cores from the tomatoes; cut the tomatoes into ½-inch-thick slices. Season on both sides with salt and pepper.

In another large frying pan over high heat, warm 2 to 3 teaspoons oil until hot but not smoking. Add the tomato slices and cook, undisturbed, until starting to soften, 1 to 2 minutes. Turn the tomatoes, drizzle with as much balsamic vinegar as you like, and sprinkle with the remaining cheese blend. Cover and cook until the cheese is melted, 1 to 2 minutes. Transfer the tomatoes to a plate, drizzle with the arugula-pistachio pesto, and season to taste with salt and pepper. Meanwhile, prepare the buns. 

In the same pan used for the patties, place the buns, cut sides down, and cook over medium-high heat until lightly toasted, 1 to 2 minutes. Alternatively, toast them in a toaster oven.

Place the bun bottoms, cut sides up, on a work surface and top each with a slider and as much peperonata relish as you like. Close with the bun tops. 

Transfer the sliders to individual plates. Serve the warm caprese salad and any remaining peperonata relish on the side.