At the Simplot plant in Heyburn, ID for the original McD’s fries. He kept a commercial fryer filled with tallow on a rolling cart that he’d put in a walk-in refrigerator when not in use… so you’re preaching to the choir.

But, the last time I spoke with a member of the Simplot family, there’s no way they will return. They’ve optimized for global consistency, and you cannot sell tallow fries in many parts of the world due to regulations and people’s dietary restrictions.