In a medium bowl, combine all of the sauce ingredients and whisk together reall well. Grab a large plastic bag and place your thinly sliced flank steak inside of it. Pour 1/3 of the sauce into the bag, then seal the bag, and shake it up to coat the steak pieces. Set aside the remaining 2/3 of your sauce.
Place the steak in the refrigerator to marinate for 1-2 hours (you may want to place the bag inside of a dish in case of spills or leaking).
After the steak has marinated and you’re ready to cook, heat 1 tbsp of your vegetable oil in a wok (or large skillet) over medium-high heat. Add the snow peas and cook, stirring frequently, until the snow peas are bright green and crisp-tender, about 2-3 minutes.
Remove the snow peas to a plate. Add 1 tbsp of oil to your wok and increase the heat to high. Add half of your marinated steak pieces (shaking off excess marinade), sear the steak until it has nice color on the pieces, about 3-5 minutes.
Remove the steak to a bowl (separate from the peas). Add your final 1 tbsp of vegetable oil to the wok and the second half of your steak pieces (again shaking off the excess marinade). Cook the same as before.
When the second batch of the steak is done, add the first half back to the wok along with any juices in the bowl. Then add the remaining 2/3 of your sauce to the wok, stirring to coat the steak. Cook until the sauce has thickened, 2-3 minutes.
Now add the snow peas back to the skillet, along with the green onion slices. Stir to incorporate and then remove from heat. Optional: Serve over rice, topping with extra green onion slices and toasted sesame seeds. Enjoy!!
NOTE: This Asian Beef with Snow Peas recipe is saucy enough to serve over rice or pasta, but if you would like it EXTRA saucy, double the sauce ingredients (use only about 1/3 cup of the sauce for the marinade and the rest for the sauce at the end). Follow all other instructions as directed above.