In a medium size mixing bowl, whisk together all marinade ingredients from the lime to the pepper jelly until well combined. Set aside.
Remove flank steak from package and, using a meat mallet or heavy skillet, tenderize for about 30 seconds until a consistent thickness.
Place steak in a large, sealable plastic bag and pour marinade over it. Marinate in the fridge for at least 1 hour up to overnight.
About 20-30 minutes before you plan to grill remove steak from the fridge so that it can come to room temperature before cooking. Preheat your grill to medium high. While the steak is coming to room temperature, slice your peppers into thin strips and combine in a medium sized mixing bowl with sliced onions. Sprinkle salt, cumin, chipotle (or chili) powder, and dried oregano over the vegetables and stir to evenly distribute.
Add 1-2 tbsp olive oil to the bottom of a cast iron skillet or other heavy pan and heat on high until hot and shimmering.
Once hot, add the veggies to the pan and press down in an even layer. Let the veggies cook for a minute or 2 undisturbed. Then stir them up again and repeat the process, pushing in a even layer and cooking on medium high/high for a minute or 2 undisturbed until your veggies are cooked through and lightly charred. Remove from the heat, cover with foil to keep warm and set aside.
Once your grill is hot, place your steak on the grill and cook with the lid closed for about 4 minutes. Flip the steak over and cook for another 3 minutes with the lid closed.
Remove steak from the grill and allow it rest for at least 5 minutes before slicing. *Note* In order to get a tender flank steak it is critical that you slice AGAINST the grain. This ensure any stringy fibers are broken up and you get a more tender bite. Serve veggies and flank steak on butter lettuce wraps with cilantro, lime wedges, sour cream and any other toppings you desire. Enjoy!