I've been buying flap meat from Costco. Kind of pricey at 4.99 a pound but it sure is delicious.
I made this marinade which I like to think is inspired by Korean Bulgogi.
1/4 Cup soy sauce (or Wheat free Tamari)
1/4 Cup water
1-2 tsp seasame oil
1 tsp of onion powder
The equivalent of around 2-3 tsp of sweetener (sugar, honey, splenda, whatever)
3-4 cloves of freshly crushed or chopped garlic
6 or so slices of fresh ginger (don't bother chopping or peeling)
Red pepper flakes (to taste)
Put the beef in the bag with the marinade and let it sit for at least a few hours. I usually take my 2-3 pounds of beef and chop it up into 4-5 oz servings and divide the marinade between two bags, along with the meat. Then one goes in the freezer for later. The other, I start using the meat from after it has had a bit of a soak.
I cook this meat about 2 minutes on each side in a pan of the stove top. The marinade will pretty much evaporate so after the meat is done, I add a bit of water to the pan and let some of the water boil off until the marinade is reconstituted. Then I pour it on top of the meat, or perhaps over a vegetable side dish.