Preheat the grill or grill pan over medium-high heat.

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.

In a small bowl, combine the ground cumin, chili powder, paprika, garlic powder, salt, and pepper. Rub the spice mixture onto both sides of the flank steak. Let marinate for at least 20 minutes or up to a day.

In a large skillet, heat the vegetable oil over medium-high heat. Add the diced onion and cook until softened and lightly browned, about 3 minutes. Remove from heat and set aside.

Grill the marinated flank steak for 2-3 minutes per side or until desired doneness. Remove from the grill and let it rest for a few minutes before slicing it into thin strips.

Warm the corn tortillas on the grill or stovetop over medium heat for about 30 seconds on each side.

To assemble the street tacos, place a few slices of grilled flank steak on each warm tortilla. Top with the sautéed onions and chopped cilantro. Serve with lime wedges on the side.

Serve the Mexican street tacos with a side of tortilla chips and salsa and a glass of cold kombucha.