1. Preheat oven to 425°.
2. Combine cumin, sugar, chili powder, ginger, 1/2 teaspoon salt, red pepper, lemon rind, and black pepper in a small bowl; rub spice mixture over both sides of chicken. Heat a large ovenproof skillet or cast-iron pan over medium-high heat. Add 1 tablespoon oil to pan; swirl to coat. Add chicken to pan, placing it skin side down; cook 5 minutes on each side or until chicken is browned. (If necessary, work in batches to avoid overcrowding the pan.) Transfer pan to oven. Bake chicken at 425° for 14 minutes or until done. Remove chicken from pan; let stand 10 minutes before serving.
3. While chicken rests, heat a small saucepan over medium-high heat. Add remaining 1 1/2 teaspoons oil to pan; swirl to coat. Add couscous and garlic to pan; cook 2 minutes or until toasted and fragrant, stirring frequently. Carefully stir in remaining 1/4 teaspoon salt and chicken stock. Bring liquid to a boil. Remove from heat; cover and let stand 4 minutes (avoid opening the lid). Fluff couscous with a fork, and stir in parsley and lemon juice.