Tenderize the meat. Pound the steak very thin with a meat mallet you want it to be an even thickness.

Marinate. Add garlic, lime, beer, salt, coriander, cumin, chili powder, and black pepper to a dish large enough to hold the steak. Whisk until everything is combined. Add meat and turn to coat in the marinade. Cover and refrigerate for at least 30 minutes (I like to give it 2 hours if possible) or overnight.

Grill vegetables. Heat a grill to medium-high heat. Toss onion and peppers with the oil and season with salt and pepper. Grill vegetables, turning occasionally, until lightly charred and tender. Remove to a plate, cover with foil and keep warm in a low oven.

Grill meat, turning once, until lightly charred on the outside and cooked to desired doneness. About 5-7 minutes for medium rare but I like to cook it a bit longer to more of a medium. Transfer to a cutting board and tent with foil. Let rest while you cook the tortillas.

Warm the tortillas. Cook the tortillas one at a time in a dry cast iron skillet until toasted on one side, flip and toast the other side then remove to clean kitchen towel to keep warm.

Slice and serve. Thinly slice the meat against the grain then slice the bell peppers into 1/2-inch thick strips and serve with the tortillas, pico de gallo, sour cream, and guacamole.