Cook your base. Make rice, quinoa, or cauliflower rice according to package directions.
Spread on a tray to steam off extra moisture, then portion into 4–5 meal prep containers.
Prep the vegetables. Chop broccoli, carrots, bell pepper, and snap peas. Keep pieces bite-sized for quick, even cooking.
Whisk the teriyaki sauce. In a bowl, combine soy sauce, rice vinegar, honey, sesame oil, water/broth, garlic, ginger, and sriracha if using. Taste and adjust sweetness or saltiness now.
Sear the chicken. Pat chicken dry and season with salt and pepper.
Heat oil in a large skillet over medium-high. Add chicken in a single layer and cook 5–7 minutes, stirring occasionally, until browned and nearly cooked through. Transfer to a plate.
Steam-sauté the veggies. In the same pan, add a splash of water if needed.
Add carrots and broccoli first, cook 2–3 minutes, then add bell pepper and snap peas. Cook until crisp-tender, about 3–4 more minutes. Remove to a bowl.
Simmer and thicken the sauce. Pour the teriyaki sauce mixture into the skillet and bring to a gentle simmer.
Stir the cornstarch slurry, then drizzle it in while whisking. Simmer 1–2 minutes until glossy and slightly thick.
Combine chicken with sauce. Return chicken to the pan and toss to coat. Simmer 2–3 minutes until the chicken is fully cooked and the sauce clings well.
Turn off heat.
Assemble the meals. Divide veggies among containers over the rice. Spoon teriyaki chicken on top. Drizzle any extra sauce evenly.
Add green onions and sesame seeds.
Cool before sealing. Let containers cool uncovered 15–20 minutes. Seal and refrigerate.