Trim the woody ends off the Brussels sprouts and halve any of the larger sprouts so that they are all similar in size. Place in a large bowl.
Add the soy sauce, vinegar, garlic, ginger, honey, and oil to a small bowl and stir well to combine.
Drizzle the sauce over the Brussels sprouts and stir to coat. Let set for 15 minutes.
Preheat the air fryer to 380 degrees for 5 minutes.
Add the Brussels sprouts to the air fryer in a single layer. Cook for 12 minutes, shaking the basket halfway through cooking. Test Brussels sprouts for doneness (they should be tender) and continue cooking for 1-2 minutes, if needed.
Remove from the air fryer and sprinkle the fried onions over the sprouts before serving.