You’ll need a medium to hot BBQ or a frypan.
Sauté the onion on medium to high heat, once it is clear add the beef (and bacon and mushroom if using it), fry until cooked through, add the sliced capsicum and fry for a further couple of minutes, just until the capsicum is soft. You don’t want to overcook it, add a dash of Worcestershire sauce and salt and pepper to taste.
If you're adding Cheese toss it through now, you want it to just melt, take off the heat and place in a serving dish.
Meanwhile, heat a fry pan or the other side of your BBQ grill and heat tortillas according to instructions. Spoon enough fajita mixture into each tortilla so that you can still hold it with one hand to eat. And some salsa (try our recipe) if you like it spicy.