Add chicken, onion, and garlic to the base of the slow cooker.
Whisk 1/2 cup of water, soy sauce, honey, brown sugar, rice vinegar, black pepper, and ginger. Pour over top of chicken, ensuring the sauce gets under and all around the chicken. Slow cook on low for 5-6 hours or until chicken is easily shreddable with a fork.
Remove chicken from the slow cooker and shred with 2 forks. Set aside and turn off the slow cooker.
Pour the sauce into a medium sauce pan over medium high heat. In a small bowl, whisk together the remaining 1/4 cup of water and cornstarch. Slowly whisk the cornstarch slurry into the sauce. Continue to whisk and let it boil until the teriyaki sauce begins to thicken, about 2 minutes.
Return the shredded chicken to the slow cooker, pour the sauce over it, and toss until evenly coated.
Prep the veggies. Add bell peppers and green beans* to a microwave safe dish and cover with a very damp paper towel. Microwave for about 1 1/2 minutes or until green beans are bright green.
Immediately transfer the peppers and sugar snap peas to an ice bath to stop them from cooking any further. Once the veggies are cool to the touch, remove to a paper towel lined plate and dry them off.
Mix veggies into the chicken until well combined.
Assemble to freeze. In a 2-cup Souper Cube, layer rice on the bottom, then chicken and veggies on top. Sprinkle with green onions and sesame seeds, then cover and freeze. Once completely frozen, remove from Souper Cubes tray and vacuum seal in a freezer bag.
Heat rice according to package instructions.
Prep the veggies. While the rice heats, heat a large skillet over medium high heat (7 out of 10). Add a teaspoon or so of oil to the skillet here if desired (not included in nutrition info). Once the skillet is hot, add sugar snap peas, peppers, and carrots. Sauté veggies, tossing frequently, until tender crisp, about 4-5 minutes. You can add 1-2 tbsp of water to help them along if needed.
Add veggies to the teriyaki chicken and mix until well combined.
Assemble. Divide rice evenly among 6 serving dishes or meal prep containers, then top with teriyaki chicken. Sprinkle with green onions and sesame seeds before serving.