Preheat outdoor grill to MEDIUM-HIGH.
Coat chicken breast halves with coconut oil and lightly season with salt and pepper; grill for 4 to 6 minutes per side.
Heat a little more coconut oil in a large skillet over medium-high heat.
Add mushrooms and pearl onions; cook and stir for 1 minute or until onions become transparent. Whisk in remaining ingredients (orange juice through gingerroot); bring to a boil then reduce heat and simmer till heated through.
Serve sauce over chicken.