Pit the avocados and scoop the meat into a mixing bowl, then mash thoroughly with a fork
Add tomatoes, onions, lime juice, cumin, sriracha, cilantro (if using), salt and pepper. Mix it all together
Seal the bowl with plastic wrap and refrigerate for 30 minutes
Preheat a pan on high heat
Butter one side of each piece of bread.
Lay bread in pan, butter side down, place 2 slices of cheese on top of each bread slice. Cover the pan with a lid to help the cheese melt faster. Grill til itu2019s toasted how you like.
Build the sandwich!