Tenderize the chicken. In a small bowl, mix together the olive oil, cinnamon, allspice, garlic, sumac, and lemon juice; add the chicken stock. Salt and pepper. Marinate overnight.
On a baking sheet, place the chicken and bake at 400 for 30-35 minutes, or until tender.
On a separate baking sheet, arrange the Brussels sprouts and onion; toss with olive oil, garlic, and salt and pepper. Roast at 400 degrees for 30-35 minutes, or until tender.
Slice the chicken; serve with the Brussel’s sprouts. Garnish with lemon or lime slices.