Preheat oven to 350 degrees F. Place your tortilla chips across the bottom of your cast iron skillet or baking sheet lined with parchment paper. Add beans evenly across the chips; sprinkle the grilled carne asada, shredded cheese, onions, tomatoes, and jalapeño slices across the chips evenly.
Repeat to build layers if you’re feeding a crowd. Bake until the cheese is melted and bubbling and veggies are warm, about 15 minutes for a single layer or 20 minutes for multiple layers. Serve immediately with your favorite toppings and don’t forget the guacamole.
While the nachos are baking, make the guacamole. Cut the avocado in half. Twist to pull apart and remove the pit. Scoop out the flesh. Place in a medium bowl and mash the avocado with a fork leaving some chunks.
Add the garlic, onion, jalapeño (optional), salt, and tomato (optional). Squeeze the lime juice over all the ingredients and give everything a gentle stir, but don’t overdo it.