Mix soy sauce, vinegar, sugar, garlic, and ginger in a small saucepan over medium heat. Stir with a whisk until sugar is dissolved.
In a small bowl, whisk together warm water and cornstarch until cornstarch is completely dissolved.
Cook the rice noodles according to the instructions on the package. Once cooked drain any exces water, cover and set aside.
Heat sauce over medium high heat. Slowly whisk in cornstarch mixture and simmer until thickened. Remove from heat and set aside.
Heat the olive oil in a nonstick pan over medium-high heat. Add diced onions and cook until soft.
Crumble ground turkey and garlic into the pan and cook until turkey is about half cooked. Add grated carrots and chopped broccoli and continue to cook until turkey is no longer pink.
Pour teriyaki sauce over cooked turkey and vegetable mixture and stir. Simmer for about five minutes to combine the flavors.
Toss with the noodles. Garnish with scallions and serve.