Combine first 5 ingredients in a jar. Cover tightly, and shake vigorously.
Pour 1/2 cup orange juice mixture into a heavy-duty, zip-top plastic bag. Set remaining juice mixture aside. Add scallops to bag; seal bag, and shake until scallops are well coated. Marinate in refrigerator 30 minutes, turning bag occasionally.
Snap off tough ends of asparagus. Remove scales from stalks with a knife or vegetable peeler, if desired. Cut asparagus into 2-inch pieces. Set aside.
Remove scallops from marinade, discarding marinade. Coat a 10-inch cast-iron skillet with cooking spray; add 1 teaspoon oil. Place over medium-high heat until hot. Add scallops, and cook 5 minutes or until browned, turning once. Remove scallops from skillet; keep warm. Add asparagus to skillet; saute until crisp-tender.
To serve, place 1 1/2 cups greens on each of 4 plates. Arrange scallops, asparagus, and orange sections evenly over greens.
Pour remaining orange juice mixture through a wire-mesh strainer. Discard garlic and gingerroot remaining in strainer. Drizzle 2 tablespoons orange juice mixture over each salad. If desired, sprinkle with orange zest and pepper.