Wash the asparagus, trim it, and cut the spears into 2-inch pieces. Place the cut pieces in a gallon-size sealable bag. Add the olive oil and water in the bag. Seal the bag. Distribute evenly in the bag by coating the asparagus completely. Preheat your Air Fryer according to directions. The Ninja shows 3 minutes. Place the asparagus in the Air Fryer basket. Bake at 390 degrees for 8 minutes.