Whisk lime juice, cola, olive oil, chili powder, salt and pepper together in bowl, then divide into 2 1-gallon freezer bags. (If freezing, be sure to label bags ahead of time.)
Let meat rest for 5-7 minutes, then slice thin (use a very sharp knife or an electric knife if you have one.)
Serve with your favorite taco toppings: shredded lettuce, avocado, salsa, etc. in your choice of hard or soft taco shells.