Teriyaki Flank Steak

(I make these with left over steak meat!)
1 lb of flank steak or skirt steak
1 large yellow onion, peeled and sliced with the grain, not against the grain as one would normally slice an onion. Slice first in half, and then slice off sections a half inch wide at widest point.
2 large bell peppers (I usually use one red and one green,) stemmed, seeded, de-ribbed, sliced lengthwise into half-inch wide strips
Marinade:
Juice of 1 lime
2Tablespoons of olive oil
2 cloves garlic, peeled, minced
1/2 teaspoon ground cumin
optional: 1/2 fresh Jalapeño pepper, seeded, ribs removed, finely chopped (be careful not to touch your eyes or anywhere near your eyes after handling a Jalapeño pepper!)
1/4 cup chopped fresh cilantro, including stems
Mix all marinade ingredients.
Set the steak in the marinade and let it sit at least an hour, the longer the better.
Heat to high heat a large cast iron pan or griddle. Add a teaspoon of olive oil to the pan. Add the steak, frying on each side for 3 minutes, or to desired doneness. 3 minutes per side will yield approximately medium rare doneness for an average cut of flank steak. If pan starts to smoke too much, reduce the heat to medium high. We want the steak browned, not burned. Remove from pan and let sit for 5 minutes.Reduce the pan heat to medium high. Add a little more oil to the pan if necessary. Add the onions, bell peppers. Cook, stirring frequently, for 5 minutes, until the onions are slightly translucent.Slice the meat against the grain into thin slices. If you slice the meat at a slanted angle, you will be able to get your slices pretty thin. Flank steak is flavorful but can be a little tough, so thin slices will really help make it easier to eat.Serve immediately with shredded cheese, salsa. shredded iceberg lettuce, sour cream, guacamole and warm flour tortillas. (Hint for warming tortillas - put in microwave over a paper towel for 20 seconds on high heat.)