Make the Spicy Mayo: In a bowl, combine the avocado oil mayo, pickled juice, hot sauce, smoked paprika, chipotle chili powder, cayenne, and a pinch of kosher salt. Adjust the seasoning to taste.
Prep the Bread: Preheat your broiler to high. Spread butter lightly on the outside of each bread slice and coat the inside with a generous layer of the spicy mayo.
Assemble and Broil: On a sheet pan, place cheese slices on the mayo side of the bread. Arrange sliced cherry tomatoes (cut side facing up) on top of the cheese. Broil for 2-4 minutes until the cheese bubbles and begins to brown slightly. Watch closely to avoid burning.
Add Remaining Toppings: Layer on sun-dried tomatoes, pickles, pepperoncini, sprouts, avocado, pickled red onion, and jalapeƱos. Add the second piece of bread, cheese side down.
Serve and Enjoy: Slice the sandwich in half and serve warm with extra spicy mayo on the side for dipping. Yum!