Separate the tender portion on the back of each breast piece and cut the remaining breast portions in half.
Melt butter in large skillet over medium heat. Add chicken pieces and garlic and sauté until chicken pieces are golden brown on both sides. Remove chicken and set aside.
Combine cornstarch with butter remaining in skillet. Stir in vinegar, sugar, salt, red pepper, chili powder, and peaches. Continue to cook over medium heat until thickened and bubbly.
Return chicken pieces to the pan and add walnuts. Stir to coat chicken pieces with sauce and continue cooking until chicken pieces are no longer pink inside.
To serve, place chicken pieces on a bed of cooked rice and spoon the peach walnut sauce over the top.
Substitute 1.5 to 2 lbs. of chicken tenders or boned thighs.