A foodie made some frites using horse-fat she bought from a horse-butcher in Nice, France and discovered that they were plum delish, so she's asked her readers for their speculation about why horse-fat makes the perfect fry:
Horse fat is unusual among quadruped fats in having a lot of highly unsaturated fatty acids, which are reactive and finicky and readily go rancid, but on the way there can give an aromatic complexity to whatever is cooked in it. The general flavor of horse may also be different enough from beef and pork to add something unusual and enriching to the fried flavor. As for the texture of the fries: horse fat isn't so different from other animal fats as to do something different to the structure of the fried potato, either crust or interior. So I think horse-fat fries come out well because the people doing the cooking in horse fat are clearly obsessives and making sure they do the best they can with this rare ingredient!
I don't have any squeam about eating horse, but man, the carbs in the potatoes scare the hell out of me.