Soak: Put frozen fries in a bowl. Cover with warm water. Soak for 30 seconds to remove excess starch.
Drain & Shake: Drain the water completely. Cover the bowl with a lid. Shake vigorously for 30 seconds to rough up the edges.
Microwave: Transfer fries to a microwave-safe dish. Cover with a lid. Par-cook in the microwave for 5 minutes at 50% power to steam the interior.
Air Fry: Spread fries in a single layer in the air fryer basket. Cook at 400°F (204°C) for 12–15 minutes. Shake the basket once or twice for even crisping.
Season: Transfer hot fries to a bowl. Drizzle with rendered fat and toss with salt. Serve immediately.