Trim excess fat from the sirloin steak and cut into bite size cubes - about 1” on each side. Combine salt, brown sugar, garlic powder, onion powder and black pepper in a small bowl.
Toss the steak in the seasoning mixture until all cubes are evenly coated. Spray air fryer baskets with cooking spray. Place steak cubes in the air fryer basket.
Air fry at 350F for 5-6 minutes for steak that is cooked to medium doneness.
While the steak cooks, prepare the simple sauce by whisking together the water, soy sauce, rice wine vinegar, sriracha and corn starch. Heat in a sauce pan over medium heat, whisking constantly until the sauce thickens. Remove from heat and pour over cooked steak bites.
Notes
For well done steak bites, cook at 350F for 8 minutes