Prep the Ingredients: Trim excess fat from the chicken breasts. Dice the broccoli, bell peppers, carrots, and snap peas into bite-sized pieces.
Make the Teriyaki Sauce: In a bowl, whisk together soy sauce, honey, rice vinegar, garlic, and ginger.
Layer in the Slow Cooker: Place the chicken breasts at the bottom of the slow cooker. Pour the teriyaki sauce over the chicken. Add the vegetables on top, arranging them evenly.
Cook: Cover the slow cooker and cook on low for 6–7 hours or high for 3–4 hours.
Thicken the Sauce (Optional): Thirty minutes before the cooking time ends, mix cornstarch with 2 tablespoons of water to create a slurry. Stir this into the slow cooker to thicken the sauce.
Serve: Remove the chicken from the slow cooker and shred or slice it into strips. Serve the chicken and vegetables over steamed rice, quinoa, or cauliflower rice. Garnish with sesame seeds and chopped green onions if desired.