Place the Marinated Beef ingredients in a ziplock bag, massage to coat then refrigerate for 2 hour to overnight.

Remove beef from marinade 30 minutes prior to cooking (to bring to room temperature) and pat dry with paper towels. Discard marinade.

Drizzle 1/2 tbsp of oil on each side of the beef (1 tbsp in total).

Heat the BBQ or a skillet on high heat. Cook beef to your liking. (Note 4)

Remove beef onto a plate and cover loosely with foil.

Return skillet to stove, still on high heat, and heat 1/2 tbsp oil. Add onions, sprinkle with salt and pepper, and cook until soft and charred. Remove onto serving plate.

Heat remaining 1/2 tbsp oil in the skillet. Add bell pepper/capsicum, sprinkle with salt and pepper, and cook until charred. Remove onto plate.

Slice beef thinly against the grain (Note 5).

Serve with warmed tortillas and fixings of choice. (Note 6)