Heat the oil in a medium skillet over medium-high heat. Add the onions and cook for 3 minutes, then add the ground beef and cook for 6 to 8 minutes, breaking up the meat into small pieces as it cooks. Drain and discard any excess grease if necessary.
Add the taco seasoning and tomato paste. Stir together until fully combined. Cook for 1 more minute. Remove the skillet from the heat and stir in the lime juice. Set aside.
Assemble the crunchwraps by adding 3-4 heaping tablespoons of the ground beef filling into the center of the tortilla and top with 2 tablespoons of nacho cheese. Spread 1 ½ tablespoons of sour cream onto the tostada shell and place it on top of the meat and cheese mixture. Add 1 ½ tablespoons each of shredded lettuce and diced tomatoes on top of the tostada.
Fold the bottom of the tortilla over the top of your fillings towards the center. Working clockwise, turn the crunchwrap and continue folding, anchoring the folded part closed with your other hand and pleating the tortilla like you are wrapping a present. Repeat until the tortilla encloses the filling.
Melt 1 tablespoon of salted butter in a large skillet over medium heat and add the crunchwrap seam side down. Lightly press on it with a spatula to help it toast evenly and seal the folds. Toast for 2 minutes or until golden brown.
Flip the crunchwrap supreme and continue toasting for an additional 2 minutes or until golden brown.
Repeat this process with the remaining wraps and butter. Serve immediately with guacamole, sour cream, or hot sauce.
Notes
Use XL tortillas. I highly recommend using extra-large 12-inch flour tortillas to hold all the fillings and fold properly.
How to make using 10-inch burrito-size tortillas: Cut out a total of 6 small circles from 2 of the tortillas. Assemble the crunchwrap as instructed above, then place the small cut-out tortilla circle in the center before folding the larger tortilla around it to seal it shut. This will yield a total of 6 crunchwraps.
Use warm tortillas. This small step really makes a difference in the assembly process and prevents your tortillas from cracking and ripping. You can use a skillet, comal, or microwave to heat them up for a few seconds on each side.
Storage: Place leftovers in an airtight container and refrigerate for up to 4 days for optimal freshness.
Reheat: Warm in the microwave for 1 minute, then toast on a nonstick skillet for 2-3 minutes on each side. You can also air fry at 390℉ for 5-6 minutes, flipping halfway through until warm and crispy.