Snap off tough ends of asparagus. Cover and cook in a small amount of boiling water 5 minutes or until crisp-tender. Drain and rinse under cold running water; drain well.
Trim white portion from green onions, and reserve for another use. Place green onion tops in a bowl; add boiling water to cover. Drain immediately, and rinse under cold running water.
Place asparagus in a 13 x 9-inch baking dish or large plastic container with lid.
Combine chopped onion and next 9 ingredients (onion through pepper) in a bowl; stir well. Pour over asparagus bundles. Cover and chill 2 to 8 hours.
Arrange asparagus on a serving platter. Spoon the marinated onion and peppers on top.