Place the beef in a bowl and season with the salt and pepper. Mix with your hands to incorporate, forming 4 to 6 patties, whichever size you wish and whatever size fits your bun. Heat a large skillet (or the grill, your preference) over medium heat and add the olive oil and butter. Cook the patties until browned on both sides and your desired doneness is reached. I do about 3 to 4 minutes per side for medium-well, but it will depend on how think your burgers are.
In a bowl, mix together the tomatoes, onion, cilantro and lime juiced, stirring well. Season with a pinch of salt and pepper.
To assemble your burgers, cover the bottom bun with avocado slices. Place the burger on top and drizzle on lots of queso cheese. Top with the pico and the jalapeños. Serve immediately.