In ziploc bag or bowl, combine steak slices with marinade and marinate for at least 4 hours in the fridge.
Heat 1 tbs light olive oil in a skillet over medium-high heat.
Add onions and stir-fry for 1-2 minutes.
Add the beef slices to the onions in the skillet and discard marinade.
Stir-fry the beef until cooked through and the liquid has cooked off. The beef should have some caramelizing on it.
Serve in lettuce leaves with Korean Sweet Potato Noodles or steamed rice, if desired.
Top with sesame seeds, chopped green onions, Korean chili sauce, or kimchi, if desired.
Korean Sweet Potato Noodles (optional filling):
Bring water to a boil in a medium pot. Add sweet potato noodles and cook for 2 minutes until softened. Drain.
Combine tamari (or soy sauce), honey, sesame oil, and pepper in bowl and mix well. Set aside.
In a skillet over medium heat, add 1 tbs light olive oil.
Stir-fry carrots until softened, about 3 minutes.
Add green onions to the pan and stir-fry another minute to wilt.
Add cooked sweet potato noodles and mix to combine.
Add sauce to the pan and mix well to heat through.
Notes
The Korean Sweet Potato Noodles for the lettuce wraps are completely optional. You can use just the beef as the filling!
Steamed rice is another good filling companion for the steak.
This recipe could work with ground beef instead of steak. If you use ground beef, there is no need to marinate it, but it should be cooked until all the liquid has cooked off.
Stir-fry the beef with other vegetables like red or yellow peppers!