Slice boneless and skinless salmon into 1-inch cubes with sharp knife.
In medium bowl, whisk together soy sauce, oil, Dijon mustard, honey, garlic, pepper and cayenne until well incorporated.
Combine chopped salmon and marinade together in medium bowl, stirring to make sure every piece is coated. Place aside and let marinade for 10 to 15 minutes.
While salmon bites are marinating, put together mango salsa in bowl by gently stirring together chopped mango, red onion, jalapeño, roma tomato, cilantro, lime juice, salt and pepper.
Preheat air fryer to 380° Fahrenheit.
Once air fryer is preheated, place salmon into basket with tongs, shaking off excess marinade, into one single layer and cook for 6 to 9 minutes, shaking it halfway. Cooking time will vary per thickness of salmon. Depending on size of air fryer basket, cooking might need to be done in tow batches to not overcrowd the basket.
Remove salmon from air fryer, then serve on top of rice if desired, and top with mango salsa.