In a blender or food processor, add all marinade ingredients. Pulse until smooth.
Combine the marinade and flank steak in a glass bowl or freezer bag and mix well to coat.
Marinate for at least 1 hour or overnight. (If using sirloin or ribeye, marinate for a maximum of 1 hour). Remove the steak from the marinade and allow excess to drip off.
Preheat the grill or a grill pan to medium-high heat (425°F). Cook for about 4-5 minutes per side (125 to 130°F for medium-rare). While the steak is cooking, add the tortillas to the grill for about 1 minute per side to warm.
Transfer the steak to a plate and let it rest for at least 5 minutes. Cut the steak into ½-inch slices across the grain, and then cut into bite-sized pieces
Serve in warmed tortillas with desired toppings such as pico de gallo, guacamole, sour cream, and cilantro.
