Pat chicken dry and cut into 1" cubes.
Place chicken in bowl, and toss well in cornstarch, pepper, and salt.
In a large skillet over medium-high heat, add the peanut oil and heat until shimmery.
Add chicken in small batches, don't overcrowd pan and cook until browned well, 2-3 minutes per side.
Remove chicken from the pan, place on a plate, repeat with the rest of the chicken working in small batches.
When done with the chicken, to the same skillet add the vegetables, garlic powder and ginger powder, saute for about 5 minutes until vegetables are tender. Add back the chicken and saute 3-5 more minutes.
Give the sauce a stir and add it to the pan, bring the mixture to boil, reduce the heat to medium-low and simmer for about 10 minutes.
Serve over a large bowl of rice, garnished with green onions and sesame seeds!