Place in the air fryer. Spray or drizzle with oil. Set to air fry for 20 minutes at 390℉.
While the Brussels sprouts are cooking, make the sauce by adding ½ cup honey and ⅔ cup red wine vinegar to saucepan over medium heat. Bring to a boil and reduce to a simmer for 3 minutes. Add ½ tsp crushed red pepper flakes. Set aside.
When the Brussels sprouts are done, they should be dark and crunchy. Toss with salt. Drizzle in the sauce. Serve.