Thursday, March 25, 2010

Duck Fat French Fries with Rosemary, Maldon Salt, and Truffle Oil

...And back to the unhealthy. (Although in my defense, I did try to make baked sweet potato fries the same day I made these, but they were just such a fail in comparison to these that I am ashamed to post about them.)

When I first read about the cold fat method of making French fries on Bitten, I was ecstatic. A way to make crispy fries without the splatter and smell of oil all over your kitchen? Genius! And then I thought, why not go all the way and really dress these fries up? I had had the rosemary truffle fries at Garden at the Cellar recently, and really, really loved them, so I picked up some fresh rosemary and white truffle oil from Whole Foods. (As another aside, did you know that most "truffle oils" on the market don't even contain real truffles? If you look at the list of ingredients, it just says "truffle flavoring" or something like that, which is code for chemicals which have never seen a truffle before. Unfortunately, I think there is only one brand of truffle oils in the U.S. that contain real truffles, and it wasn't available at Whole Foods.)


I also had a box of Maldon salt I had picked up from Christina's Spices in Inman Square. I'd rave about this salt myself, except it's already been done by so many people with so much more cooking cred than me. Needless to say, this is pretty much one of the best finishing salts you can buy. What I really love about this salt, other than the taste, is what a tactile experience it is to crush the flakes between your fingertips.

And of course, I had duck fat. Oh, how I love thee, duck fat. Especially with potatoes. (And don't forget, duck fat is better for you than butter!)

I used the potatoes I had received in my Boston Organics delivery. I'm not sure what exact kind they were, but they were relatively small and, I believe, from Prince Edward Island.

Duck Fat French Fries with Rosemary, Maldon Salt, and Truffle Oil (method pretty much taken word for word from Bitten)

Potatoes, peeled
Enough fat to cover the cut potatoes (duck fat, peanut oil, etc., or any combination thereof)
Fresh rosemary
Maldon salt
Truffle oil

Cut your peeled potatoes into whatever shape you like, but probably no skinnier than three-eighths of an inch. Rinse them and shake off the water (part of the genius of this technique is that a little residual water won’t cause splattering, so you don’t need to towel-dry the potatoes). Put them in a heavy pan — a straight-sided sauté pan is ideal, but anything not too shallow will do. They should ideally be in a single layer, but this is not always practical: aim for it, though. Add room-temperature fat just to thoroughly cover and put the pan over low heat, without a lid.


As the oil temperature slowly rises, the potatoes will, in effect, poach in fat and their excess water will gently evaporate (hence the lack of splattering). Yes, the oil will bubble, but reassuringly, not alarmingly. Every now and again, use a thin-bladed spatula or a long-handled spoon to make sure they are not sticking (their starch has a tendency to cause this) and give the pan a shake. Be very careful: at a certain point they will be very, very fragile — cooked but not yet crisp.


When the potatoes are very tender, you can raise the heat, but only a little. Say, from low to medium-low. They will finally start to crisp and turn golden, and will ultimately become french fries. Excellent ones. The one down side (apart from the limit on quantity) is that this can take as long as an hour.


When your fries are starting to brown, throw in some of the fresh rosemary. When your fries are sufficiently crisp and browned, remove fries and rosemary with a slotted spoon and drain. Drizzle a little truffle oil on top. Grab a pinch of Maldon salt and crush between your fingers to sprinkle on top. Repeat to taste.


I'm pretty sure you could make these French fries with regular oil instead of duck fat, with regular sea salt instead of Maldon salt, and without the rosemary and truffle oil, and they would still taste great. I was kind of surprised by how non-greasy these were on the inside. I figured that having the potatoes sit in fat for so long would've meant they would've been soaked in grease, but in actuality, they tasted more like a light and fluffy baked potato on the inside while staying nice and crispy on the outside. In other words, perfection.
Another thing I really like about this method of making French fries is that because the oil was kept at relatively low temperatures, the fats were not too damaged and you can save and reuse the fat for another French fry making session. Which I'll probably be doing real soon....

Next:  Apple Tarte Tatin
Previously:  Lemon Angel Food Cake
One year ago:  Cincinnati Chili


  1. I truly believe that the fries at Garden At the Cellar are the best fries in the ENTIRE WORLD. I still have yet to have a better fry, and I've dried them at lots of places!

    This version looks fantastic too! The fake truffle oil is pretty good. :) Honestly, I bet the real stuff will taste much more subtle, and we might actually think it doesn't have enough "truffle" flavor.

  2. Actually, I did get to try organic truffle oil at last year's Taste of the Nation, which is where I learned about the prevalence of fake truffle oil. The real stuff was pretty good, but perhaps a blind taste test is in order...

  3. Properly deep fried food shouldn't be greasy. However, I've always heard frying at too low of a temperature will make something greasy. Maybe this isn't because as the oil gets hotter, the steam coming out of the potatoes starts pushing the oil out? Maybe fried food only gets greasy if you cook it too long, or if you cook it hot and then lower the temperature. Or maybe because of the nature of the potatoes they can't really soak up the oil?

    1. this is because when frying foods in low temperatures, the food absorbs all the oils instead of developing a crispy outer layer quickly

  4. omg. i want. now.

  5. Those look divine, I'm seriously going to have to try this!! Thanks for posting!

  6. It's actually the way fries are made in general.
    They are blanched (300~315f) than fried (375f ish). When the fries are blanched the starches are converted to sugars, then when fried the sugars caramelize forcing out the fat and making the fry crispy.
    Made duck fat buttermilk biscuits today lol. and I have 500g of it from our duck leg mise en place will try your recipe. ^^

  7. Tried this with the left over duck fat from our Thanksgiving chopped liver. I had two batches so the first was with the room temp duck fat and the other in the heated fat. I have to say the second batch worked out much better than the first. I did not par-boil the potatoes since they were sliced so thin (shoestring/mandolin). It did take about 35-40 minutes for the first batch and 15 for the second.

  8. i'm making duck breast tonight and i want to do something with all the fat. i have to add my two cents about the best fries i've ever tried: they came from saffron, a place in downtown minneapolis. so good i could eat them plain and be content but they are served with sheep feta fondue. yum.

  9. Here's why cold frying this way is probably delicious but extremely greasy: when you fry something it's a battle of steam coming out of the fry and oil going in. The reason you should fry potatoes at the proper temperature (~320ºF the first time, ~375ºF the second) is that at that temperature there is enough steam coming out of the fry to prevent too much oil from getting in. If you cold fry the fries then the oil can easily get into the fry making it greasy. So these probably taste great, but you're not going to get the nice texture you want and it's probably 2-3 times as unhealthy as a properly fried fry.

    1. I used to believe that was true until I tried these fries. The insides weren't greasy at all, almost more like a baked potato. I can't attest to how much healthier or unhealthier it is, but I guess if that was important to someone, they wouldn't be eating fries anwyays. =)

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