Set a 14-inch wok or 12-inch frying pan over high heat. When hot, add oil, ginger, and garlic; stir until garlic begins to turn golden, about 30 seconds. Stir in asparagus and add 3 tablespoons water; cover and cook just until asparagus is bright green, 1 to 2 minutes. Add shrimp and stir, uncovered, until they are opaque in center of thickest part (cut to test), 2 to 3 minutes.