Preheat the air fryer. Set it to 400°F (200°C) for 3–5 minutes. A hot basket helps the glaze caramelize and prevents sticking.
Make the glaze. In a small bowl, whisk maple syrup, Dijon, whole-grain mustard (if using), soy sauce, lemon juice, grated garlic, olive oil, salt, pepper, and smoked paprika.
Taste and adjust salt or lemon as needed. It should be sweet, tangy, and slightly savory.
Prep the salmon. Pat the fillets dry with paper towels. Dry fish browns better and helps the glaze stick.
Lightly season with a pinch of salt and pepper.
Glaze the top. Brush most of the maple Dijon mixture over the top and sides of the salmon. Reserve a tablespoon or two to brush on after cooking, if you like a glossy finish.
Prep the basket. Lightly spray the air fryer basket with nonstick spray or use a perforated air fryer parchment liner. If your salmon has skin, place it skin-side down.
Air fry. Cook at 400°F (200°C) for 7–10 minutes, depending on thickness.
A 1-inch thick fillet usually needs about 8 minutes. The salmon should flake easily and reach an internal temperature of 125–130°F for medium or 140°F for fully cooked.
Optional finish. Brush on the remaining glaze during the last minute for extra shine and flavor. If you like a deeper caramelized edge, cook 1 more minute.
Rest and serve. Let the salmon rest for 2 minutes.
Garnish with chopped parsley or chives and serve with lemon wedges. Plate with rice, roasted vegetables, or a simple green salad.