In a saucepan, combine the sweet-and-sour sauce, orange juice, onion and garlic. Bring to a boil, reduce the heat and simmer for 5 minutes. Remove the saucepan from the heat and set aside.

Cut the chicken breasts in half lengthwise. Grill over high heat for 4 to 8 minutes on each side, depending on the thickness, until thoroughly cooked and an instant-read thermometer inserted in the thickest part of the chicken breast reads 160° F. Baste the chicken with the sweet and sour sauce during last 5 minutes of cooking. Remove from the grill and keep warm.

In a wok, heat the vegetable oil. Carefully add the broccoli, peas and carrots and stir fry for about 5 minutes or until the vegetables are crisp tender. Add the rice and stir with a wooden spoon to combine all the ingredients and heat through. Add the soy sauce and stir to mix.

Serve the chicken with the rice, garnished with cilantro and green onions.