To marinate chicken: Combine marinade ingredients and toss with chicken to combine. Set aside to marinate at room temperate for 15 minutes before grilling.
To prepare quinoa: Heat heavy sauce pot over medium high heat. Add enough oil to coat the bottom of the pan. Add the onions and sauté until tender and golden brown. Add quinoa to the pot to toast for about 30 seconds before adding the broth. Bring to a boil, reduce the heat to a simmer and cover. Cook for about 15 minutes.
To cook chicken: Add the chicken cubes to skewers (soak the skewers in water to prevent burning). Grill at 375 until fully-cooked.