Stir the picante sauce, honey, soy sauce, ginger and 5-spice powder in a medium bowl. Pour half the picante sauce mixture into a 2-quart shallow, nonmetallic dish or gallon-size resealable plastic bag. Cover and refrigerate the remaining picante sauce mixture.
Place the steak into the dish or the bag and turn to coat. Cover the dish or seal the bag and refrigerate for 1 hour. Remove the steak from the marinade. Discard the remaining marinade.
Lightly oil the grill rack and heat the grill to medium. Grill the steak for 10 minutes for medium rare or to desired doneness. Remove the steak from the grill and keep it warm.
Brush the onion slices with the oil and grill for 10 minutes or until tender, turning the onion slices over once during grilling.
Cut the steak into thin slices. Serve with the onion and remaining picante sauce mixture.