Prepare sauce- In a jar or salad dressing shaker, add the soy sauce, maple syrup, water, sesame oil, red pepper flakes, mirin, garlic, ginger and cornstarch. Shake it up, then set aside.
Cook vegetables & edamame- Heat oil in a large pan over medium heat. Add the vegetables and edamame. Stir, cooking for 5-7 minutes, until vegetables are softened, but still retain some crisp.
Add sauce and thicken- Shake the teriyaki sauce back up, then pour evenly over the vegetables and edamame. Stir it up with a spatula, and simmer for 1-2 minutes, until the sauce has thickened and coats the vegetables evenly.
Serve- Serve the stir fry over rice, and enjoy!