Combine vegetables, water, and seasoning packet from couscous in a large saucepan; bring to a boil. Add couscous, stirring well. Remove from heat; cover and let stand 5 minutes or until liquid is absorbed. Stir in 1 tablespoon dressing.
While couscous stands, remove and discard stems from spinach. Wash spinach, and pat dry with paper towels. Slice spinach, and place in a large bowl. Drizzle remaining 3 tablespoons dressing over spinach, and toss well.
Spoon couscous mixture over spinach, and sprinkle with cheese.