Mix the soy sauce, maple syrup, and sherry together in a small bowl.
Heat 2 tablespoons of the oil in a large, nonstick heavy-bottomed skillet over high heat until almost smoking. Add the asparagus and cook, stirring frequently, until well browned, about 5 minutes.
Clear a space in the center of the pan, add the garlic, and drizzle with the remaining ½ tablespoon oil. Cook until fragrant, about 30 seconds, then mix with the asparagus.
Add the soy sauce mixture and toss to coat the asparagus. Cook until the sauce is syrupy, about 30 seconds.
Sprinkle with the scallions and serve immediately.
