Combine ground beef, taco seasoning, and carne asada seasoning in a medium bowl. Use your hands to mix the seasonings and beef together well. Then roll the meat mixture into nine equally sized balls that are about the size of a golf ball. Set the burger balls to the side while you prep the other ingredients.
Mix the sour cream and hot sauce together in a small bowl. Refrigerate until ready to use as a burger topping. Make sure that all other burger toppings are prepared and ready to serve. *I highly recommend using guacamole, pico de gallo, and a bit of shredded romaine lettuce for your taco burger toppings.
Heat griddle on medium-low to medium until it reaches about 425-450 degrees F.
While griddle is heating up, toast the bread rolls on the griddle cut side down until lightly golden brown. Then, remove from the griddle and set aside while burgers cook.
When griddle is hot, add about 1 tablespoon of your favorite cooking oil and spread it around a bit with your spatula. Place the burger balls on the oiled surface, making sure that you have enough space to smash and flip them. Place some of the thinly sliced onion and jalapeños on top of each burger ball.
Place a piece of parchment paper over the first ball, and use your burger press or a stiff spatula to press down until the burger patty is evenly thin and flat. Once the burger is smashed, apply pressure using the press or spatula for about 8-10 seconds. Repeat the process for the other burger balls, working quickly so that the smashed taco burgers do not overcook.
When burgers are about 60-70% cooked through (and there are still some pink spots on top), use a spatula or scraper to flip the burgers to the second side, making sure to scrape under the burger crust to remove it from the griddle with your burgers. Immediately after flipping the taco burgers, top each patty with an equal amount of shredded cheese.
When the cheese is melted (probably less than 1 minute), remove the burger patties from the griddle and transfer to a plate to rest. *If needed, you can also move the patties closer together on the griddle and cover them with a melting dome to help the cheese melt faster.
While burgers are resting, spread a dollop of guacamole on the bottom toasted buns. Then, top each bottom bun with 3 burger patties, overlapped a bit to mimic the shape of the bolillo rolls (or whatever buns you are using). Top the burgers with shredded lettuce, pico de gallo, and a drizzle of the spicy sour cream. Add the top bun and serve the taco burgers immediately. Enjoy!