Begin by prepping all your ingredients. Cut the chicken into bite-sized pieces, slice the red bell pepper, and chop your mixed vegetables. Drain the water chestnuts and slice the green onions, keeping the white and green parts separate.
In a bowl, whisk together the water, low-sodium soy sauce, honey, rice vinegar, minced garlic, minced ginger, and red pepper flakes. Set this mixture aside as it will be the flavorful teriyaki sauce for our stir fry.
In a large wok or skillet, heat 1 tablespoon of extra-virgin olive oil over medium-high heat. Once hot, add the bite-sized chicken pieces. Season lightly with salt and pepper and cook for about 5-7 minutes, until the chicken is golden brown and cooked through. Remove the chicken from the pan and set it aside.
In the same pan, add the remaining 1 tablespoon of olive oil. Add the red bell pepper, mixed vegetables, and water chestnuts. Stir-fry for about 3-4 minutes until the vegetables are tender-crisp.
Return the cooked chicken to the pan with the vegetables. Pour the prepared teriyaki sauce over the chicken and veggies. Stir well to combine. Let the mixture simmer for about 2 minutes. Then, stir in the cornstarch slurry to thicken the sauce, cooking for an additional minute until it coats everything nicely.
Remove from heat and garnish with the chopped green onions and sesame seeds if desired. Serve the teriyaki chicken stir fry over your choice of brown rice, quinoa, noodles, or cauliflower rice.
