Gather all the ingredients you will need.
Score the flank steak with a sharp knife.
Add the steak to a ziplock bag with fresh oregano.
Roughly chop the white onion and garlic and add to the bag with the steak.
Combine tequila, lime juice, orange juice, and soy sauce in a bowl. Reserve ½ cup. Pour into the bag.
Seal and let marinate for 2 hours.
Remove steak from the bag.
Remove garlic and onions from marinade and add to a saucepan with reserved marinade. Place into the smoker as it preheats. Preheat the smoker to 500 degrees.
Combine garlic paste and olive oil in a small bowl and brush over the steak.
Season with cumin, pepper, ancho chili powder, and salt.
Place steak directly on the prepared grill grates. Cook 5 minutes per side, leaving it to cook after flipping once. Reduce smoker temperature to 225 degrees.
After 10 minutes, brush with marinade. Cook until internal temp reads 125 degrees. Start checking after 60 minutes but should not take longer than 90 minutes.
Remove from heat and let rest on a wooden cutting board. Drizzle with the marinade, then thinly slice.