Make the salsa: Add all ingredients (except the tortilla chips) to a blender and pulse until mixed well. Season with salt and pepper to taste. Set aside.

Marinate the Carne Asada: In a bowl, combine sliced flank steak, olive oil, minced garlic, lime juice, cumin powder, chili powder, salt, and black pepper. Allow the steak to marinate for at least 30 minutes.

Cook the Carne Asada: Heat a grill or grill pan over medium-high heat. Grill the marinated flank steak for 3-4 minutes per side or until it reaches your desired level of doneness. Remove from heat and let it rest for a few minutes before slicing it thinly.

Warm the Tortillas: Heat the flour tortillas in a dry skillet or microwave for about 20 seconds to make them pliable.

Rinse and drain the black beans. Pour into a saucepan and warm over medium heat.

Assemble the Burritos: Lay out each tortilla. Layer with black beans. sliced carne asada, shredded lettuce, and avocado. Finish with a dollop of sour cream.

Fold and Roll: Fold the sides of the tortilla inwards, then fold the bottom up and roll tightly from the bottom to create a burrito.

Mix the ingredients for the lemon sparkling water, serve over ice if desired.

Serve: Cut each burrito in half. Serve immediately with chips, salsa, and lemon sparkling water.