Whisk together marinade ingredients and pour over sliced flank steak. Marinate in refrigerator for at least 1 hour.
Whisk together sauce ingredients and set aside.
Heat sesame oil over medium-high heat in a wok. Add garlic, ginger, and red pepper flakes and sauté until fragrant.
Add asparagus, snow peas, carrots, and bell pepper and sauté for 3-4 minutes until tender crisp. If you don't have a wok, use a large skillet instead. After adding the veggies and tossing them with the garlic, add 2 tbsp water and cover for about 2 minutes to help them cook. Set aside.
Add olive oil to wok, then add flank steak and sear on one side for about 1 minute. Flip the steak and sear on 2nd side for about 1 minute. Add sauce and bring it to a boil for 1-2 minutes to thicken it.
Return veggies to wok and toss with steak and sauce. Serve over your favorite rice.
Notes
I didn't include the rice in the recipe/nutrition info since I know many people have a favorite type of rice that they'll want to use. I was feeling lazy and used a packet of 90-second brown basmati rice.