In medium mixing bowl, whisk together oil, vinegar, lemon juice, soy sauce, sugar, garlic, ginger and salt and pepper. Pour over thighs, cover and refrigerate overnight. Grill skin side down over medium heat 8 to 10 minutes. Flip, brush with marinate and cook 4 to 6 minutes more. Skewer onions, brush with marinade and grill a couple of minutes a side. Serve chicken and onions over rice.