Grate 1/4 teaspoon orange rind, and set aside. Squeeze juice from orange over a bowl; reserve 1/4 cup juice, and set aside. Add water to remaining juice in bowl to equal 1 cup.
Bring water mixture and salt to a boil in a medium saucepan; gradually stir in couscous. Remove from heat; cover and let stand 5 minutes. Fluff with a fork. Cool slightly. Stir in orange rind, beans, bell pepper, onions, and parsley.
Combine reserved 1/4 cup orange juice, vinegar, oil, and cumin. Add couscous mixture; toss well. Store salad in an airtight container in refrigerator.