In a large bowl, mix the guava nectar, rice wine vinegar, sugar, oyster sauce, soy sauce, and salt. Place the chicken in the bowl, cover, and marinate 30 minutes in the refrigerator.

Drain the chicken, reserving remaining marinade. Place cornstarch on a plate. Dip the chicken in the cornstarch to coat.

Heat the oil in a skillet over medium heat. Cook and stir the chicken until no longer pink and juices run clear. Remove chicken from the skillet, and set aside, reserving remaining oil and juices.

Place a steamer basket in a pot over boiling water, and steam the broccoli 2 minutes, or until tender.

In the skillet with the reserved oil and juices, cook and stir the orange zest and garlic for about 1 minute. Pour in the remaining marinade, and bring to a boil. Cook 5 minutes, or until thickened. Toss the chicken and broccoli in the skillet, and cook until heated through and coated with the marinade. Place chicken in the center of a platter. Arrange orange slices and broccoli around the chicken to serve.