To prepare sauce, bring orange juice to a boil in a large saucepan; cook until reduced to 1/3 cup (about 6 minutes). Stir in 1 1/2 tablespoons liqueur. Pour into a small bowl, and set aside.
To prepare couscous, bring apple juice, 3 tablespoons butter, and salt to a boil in a saucepan, and gradually stir in couscous and rind. Remove from heat; cover and let stand 5 minutes. Fluff with a fork.
To prepare topping, melt 2 tablespoons butter in a medium nonstick skillet over medium-high heat. Add sugar, and cook 1 minute, stirring constantly. Stir in apple and raisins; cook 5 minutes or until apple is tender, stirring frequently. Remove from heat. Stir in ginger, 1 1/2 tablespoons liqueur, and cinnamon.
Spoon about 1/3 cup couscous into each of 8 dessert glasses or bowls. Top each serving with about 2 tablespoons topping, 1 1/2 teaspoons sour cream, and about 1 tablespoon sauce. Garnish with mint sprigs, if desired.