Combine first 5 ingredients, stirring with a whisk.
Pat orange sections dry with a paper towel. Slice each roll in half. Layer bottom of each roll with 1/2 cup Basic Grilled Flank Steak, 1/4 cup baby spinach, 1 tablespoon cheese, and 1/4 cup orange sections. Drizzle each serving with about 2 teaspoons vinaigrette; top with top halves of rolls. Wrap in aluminum foil or wax paper; chill.