Put all the ingredients for the marinade in a big bowl, mix well and add the steak. Seal the bowl with cling film and let the flavors get into the meat for about one hour.
Take a frying pan or skillet and heat it without using butter or oil and put the steak in. Don’t throw away the marinade, you’ll need it later. Cook the steak for ± 3 min on each side and then take the meat out of the pan. Wrap the steak in tin foil and let it rest for 3 to 4 minutes. Use the same pan for the vegetables. Put the bell peppers, red chili and onion in the pan and add the marinade. Cook the vegetables in about five minutes until the onion is glazed but the veggies still have some bite.
Use a good meat knife and slice the steak (across the grain) into thin strips. Place the strips on a plate and put the vegetables next to the juicy meat strips. Top off the dish with the avocado and tomato and sprinkle the chopped cilantro on the dish for finish.
When you are not on a diet you can serve this dish with some warm tortilla wraps.