In a small bowl, combine tomatoes with green onions; stir well and set aside. In a large saucepan over medium heat, add ground beef and cook half way before adding taco seasoning; stir well. When the meat is almost cooked, add pickled jalapeños and gently combine. Remove from the heat and transfer into a colander to drain the fat very well to prevent the sandwich from getting soggy.
To assemble the sandwich, working on only 4 slices bread, spread a thin layer of sour cream and then add about ¼ cup of Cheddar cheese over. Distribute beef mixture evenly on top of the cheese. If you want spicier, add a few drops of hot sauce over the meat.
Place avocado pieces on top of the meat followed by a ¼ cup of Pepper Jack cheese on each. Spoon tomato mixture over evenly and to hold everything in place, add another ¼ cup sharp Cheddar cheese on top. Add 1 tablespoons salsa per slice and sprinkle with cilantro. Place a slice of bread, press down gently and spread a thin layer of butter, covering the entire surface.
Place sandwiches on a baking sheet lined with foil and transfer to the oven under the broiler with the rack positioned about 8-inches from the top. When they get nice and brown, remove from the heat, carefully flip them over and butter the other side with a thin layer of butter. Return to the oven and broil until golden brown. Remove from the oven and serve immediately.