Cut steak into 1 to 1.5-inch cubes with even size for uniform cooking.
Pat cubes dry thoroughly with paper towels.
Toss cubes with 1–2 teaspoons high smoke point oil and sprinkle with salt, pepper, and garlic powder evenly.
Preheat the air fryer to 400°F (200°C). Arrange steak cubes in a single layer in the basket with space between pieces.
Air fry at 400°F for 8 minutes, tossing halfway through, until browned outside and internal temperature reaches 130°F to 140°F (medium rare to medium).
Remove and let rest briefly for 5 minutes to redistribute juices.
Optionally toss with melted butter and minced garlic for richness before serving.