Preheat the air fryer to 400°F (200°C).
In a small bowl, mix together the mayonnaise and Dijon mustard.
Season cod fillets with salt and pepper.
Spread the mayo-mustard mix over the top of each fillet.
Press sesame seeds into the coated side of each cod fillet.
Spray the air fryer basket with cooking spray and place cod fillets, sesame side up, in the basket.
Air fry for 10–12 minutes or until the fish flakes easily with a fork.
Toss sugar snap peas with olive oil, salt, and pepper.
Add snap peas to the air fryer during the last 5 minutes of cooking.
Serve the cod with the air-fried snap peas on the side.