In a bowl, combine tuna, dill pickle mayo, Dijon mustard, chopped pickles, pickle brine, garlic, grated onion, celery, and fresh dill.

Season with salt and pepper and mix until creamy and evenly combined.

Lightly butter the sourdough and toast it in a skillet until golden and crisp.

Place a slice of provolone on the toasted bread.

Let it melt slightly before adding the tuna salad. This creates a little cheese shield that helps keep the bread crisp.

Pile the pickle tuna salad on top of the melted cheese.

Add another slice of provolone and place the sandwich under the broiler until the cheese melts and bubbles.

Once the cheese is melted, top the tuna melt with dill pickle slices and fresh dill.