Pat the salmon fillets dry with paper towels to remove excess moisture, ensuring a crispy skin.
In a small bowl, whisk together the mustard and lemon juice for a zesty glaze.
Using a basting brush, lightly coat the skin of each salmon fillet with olive oil to help the skin crisp up.
Spread the mustard mixture evenly over the top of the salmon fillets, covering the flesh and some of the skin for flavor.
Sprinkle salt and freshly ground pepper over the fillets to season, enhancing the overall flavor.
Preheat your air fryer to 400°F (200°C) for a few minutes until hot and ready.
Place the salmon fillets skin-side down in the air fryer basket, making sure they are not touching for even cooking.
Cook the salmon in the air fryer at 400°F (200°C) for about 8 minutes, watching as the skin puffs up and crackles into a crispy, golden crust.
Once cooked, carefully remove the salmon from the air fryer and let it rest for a minute to settle the juices.
Squeeze fresh lemon over the fillets and sprinkle with chopped dill or parsley if desired for added freshness.
Serve immediately, enjoying the crackling skin and tender, flaky flesh for a perfectly crispy and flavorful salmon experience.