Step 1: Preheat the Oven - Begin by preheating your oven to 400°F (200°C).
Step 2: Prepare the Marinade - In a mixing bowl, whisk together the soy sauce, brown sugar, sesame oil, minced garlic, grated ginger, cornstarch, and water until well combined.
Step 3: Marinate the Chicken - Place the chicken breasts in a large resealable bag or a shallow dish. Pour half of the teriyaki marinade over the chicken. Seal and let it marinate in the refrigerator for at least 30 minutes.
Step 4: Prep the Vegetables - While the chicken is marinating, wash and slice the broccoli, carrots, red onion, and bell pepper. Season with salt and black pepper.
Step 5: Assemble on the Sheet Pan - Spread the marinated chicken and prepared vegetables evenly on a large sheet pan. Drizzle the remaining marinade over the top.
Step 6: Roast in the Oven - Place the sheet pan in the preheated oven and roast for approximately 25-30 minutes, until the chicken is cooked through and the vegetables are tender.
Step 7: Serve and Enjoy - Let it sit for a couple of minutes before serving. Serve over rice, quinoa, or enjoy on its own.