That's what we use for making the best french fries in north of France and Belgium. Beef tallow and double cooking bath.
Discussion
What's a double cooking bath?
Like two friers so you can double fry things?
All have their own techniques, but basically is: 2 cooking baths at different temperatures.
You have to cook them once, take them out, let them rest for a few minutes, and then cook them a second time.
That way, you get a crispy outside and a soft, mashed inside. 👌