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 halfway before adding taco seasoning; stir well.
When the meat is almost cooked, add pickled jalapeños and gently combine.
Remove from the heat and transfer to a colander to drain the fat very well to prevent the sandwich from getting soggy.
Preheat oven to broil.
Line a baking sheet with foil, set aside.
To assemble the sandwich...Working on only 4 slices of bread, spread a thin layer of sour cream and then add about ¼ cup of Cheddar cheese on top. Distribute the beef mixture evenly on top of the cheese. If you want it 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 the tomato mixture over evenly and to hold everything in place, add another ¼ cup sharp Cheddar cheese on top.
Add 1 tbsp. salsa per slice and sprinkle with cilantro. Top with a slice of bread, press down gently and spread on a thin layer of butter, covering the entire surface.
Place sandwiches on the prepared baking sheet 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.