Prep the air fryer. Preheat your air fryer to 350°F (175°C) for 3 to 5 minutes. A warm basket helps the chips crisp faster.

Peel the celery root. Trim off the top and bottom to create flat surfaces. Stand it upright and slice off the rough, knobby skin with a sharp knife. Rinse to remove any dirt, then pat dry.

Slice thinly. Using a mandoline set to about 1/16 to 1/8 inch (1.5–3 mm), slice the celery root into rounds. If using a knife, go slowly and aim for uniform slices so they cook evenly.

Optional soak for extra crispness. Place slices in a bowl of cold water for 10 minutes to remove some starch. Drain and dry thoroughly with a clean towel. Dry slices are key to crunch.

Season. In a large bowl, toss slices with oil, salt, pepper, and any optional seasonings. Use your hands to coat evenly without drenching them in oil.

Arrange in the basket. Spread slices in a single layer in the air fryer basket. It’s okay if edges touch, but avoid heavy overlapping. You’ll likely cook in batches.

Air fry. Cook at 350°F (175°C) for 8 to 12 minutes, shaking the basket or flipping slices halfway. Watch closely in the last 2 to 3 minutes—they can go from golden to too dark quickly.

Finish and season again. When slices are golden with crisp edges, transfer them to a cooling rack or paper towel–lined plate. Sprinkle with a pinch more salt while hot. Add lemon zest or a tiny squeeze of lemon if using.

Repeat. Continue with remaining slices. Serve warm, or let them cool fully for maximum crunch.