Nerding it up with potato gratin

Potato gratin

Potato gratin makes me anxious. I'm not anxious to eat it, of course — who would be? — but rather I never feel in control. You're expected to submit to the oven a tray of soupy, raw potatoes and end up with a creamy, tender, caramelised final product. What if the potatoes are undercooked, though? What if it's too wet? It's just too much pressure.

I'm a big fan of scalable formulas in cooking. I have a few stored away already: pasta (1 egg per 100g flour), shortcrust pastry (1 part butter, 3 parts butter, 4 parts flour), and quiche custard (1 egg, 1/3 cup cream, 1/3 cup milk) all work pretty well for the amounts I cook. What's more, by using these over and over I get a sense for what 'just right' looks and feels like, to the point where in some cases I don't need to use them at all. What I need is a formula for potato gratin.

I should warn you now that this entry doesn't contain a tried-and-tested formula, just some preliminary notes. I searched Google for "potato gratin recipe" and looked at a handful of results to see what ratio of potatoes to cream were used. Exclusion criteria were recipes that mixed cheese in with the potatoes (rather than simply on top), recipes with milk or other liquids (because it just gets tricky), and those that didn't include potato weight (seriously, what the hell is '1 average potato'?).

The ratio, r is simply volume of liquid (ml) / weight of potatoes (grams). So for any given weight of potatoes, multiply by r and that's how much liquid to use. Hypothetically.


In addition to learning that I am a huge nerd, we can also see that the ratio tends to be around 0.45. Of course, there's more to potato gratin than potato and cream. There's cooking time, oven temperature, and the shape of the dish. A shallow gratin will cook quicker, a hotter oven will brown the top faster, and a longer cooking time will reduce the cream more. Within the next couple of weeks I hope to test these results using different ratios and dish sizes. Then I'll eat the results and put on 10kg. It'll be awesome.

Meanwhile, here's the recipe for a gratin I made the other night which worked out really well. You'll see that I wussed out and cooked the potatoes in cream first, but hey, Thomas Keller does it so it can't be that bad.

Potato gratin


  • 725 g désirée potatoes, peeled
  • 1.25 cups heavy cream
  • 1/2 cup water
  • A few gratings of nutmeg
  • 1 tsp dijon mustard
  • 2 cloves of garlic, halved
  • 3 sprigs of fresh thyme (or 1/3 as much dried thyme)
  • 5 peppercorns
  • 1 bay leaf
  • Salt, to taste

1. Use a mandoline or sharp knife to cut the potatoes into thin slices. Wrap up the thyme, bay, peppercorns, and one clove of garlic in cheesecloth, and tie with string to make a neat little package.
2. Combine the cream, water, mustard, and nutmeg in a high-sided frying pan, then add the herb parcel and bring to a very low simmer. Simmer for 5 minutes to begin infusing. Salt the cream very generously — it should taste about the upper limit for what would be palatable, but not ridiculous1.
3. Preheat the oven to 180ºC/350ºF. Add the potatoes to the infused cream (keep the herbs in there as well) and cover. Simmer very slowly until the potatoes are just tender.
4. Rub the sides of a medium-sized baking dish with the cut side of a halved clove of garlic, the discard the garlic. Remove the potatoes from the pan into the baking dish, being careful not to break them as they'll be somewhat fragile. Discard the herb parcel.
5. Pour the cream over the potatoes, and bake until the potatoes are tender and the crust is golden.

(1) Once you add the potatoes it won't be excessively salty.

Fine times in McLaren Vale


Figure 1: Relationship of wine posts to thesis writing.

An independent study recently found a long-suspected negative correlation between the writing of a thesis and the writing of wine posts (figure 1). A thesis, these authors concluded, takes an inordinate amount of time and, as such, prevents the writing of other, more enjoyable things.

That being said, I have no idea why it's relevant here. Even, hypothetically, if I had just completed a thesis, why would I feel compelled to bring it up here? Surely I would put it behind myself as soon as possible and return to the fun task of reliving tasty wine times. I certainly wouldn't be so crude as to bring it up as some awkward excuse for my being so remiss in my duties to the second pancake. And, God forbid, if I did such a thing there's no chance at all that I would then spend a paragraph pretending that I didn't. I think we can all agree that we're above such unnecessary hand-wringing.

In other news, going wine tasting is a remarkable thing. Imagine if you could drive for half an hour and chat to the farmer who grew your tomatoes, and discuss the soil, the weather, the techniques he uses, and his suggestions for the best way to use them. And imagine that, down the road, the dairy farmer welcomes you to her house where she delights in showing you her best cheeses and the new batch of butter she has just freshly churned. Next door, an old Italian couple lead you through their herb garden where you can compare notes about the best way to make pesto or how soon to pick mint and the best time of year to plant sage. This couple then recommend that you visit their friends over the hill, who bake fresh bread every day with their own grain. Now imagine heading home with bulging bags and creating a meal with everything you'd picked up. A meal that is enjoyable for not just its taste, but it's history. You know the name of the person who grew these beans, you've shared a joke with the people who dug these potatoes, you've shared stories with the friend who collected these eggs.

This is the beauty of wine tasting. Not because you get to try a wonderful new range of wine each time (though this is wonderful), but because you get to meet the people behind the products that you love. On Friday I was in McLaren Vale, less than an hour south of Adelaide. I started at Geoff Merrill, who really ought to be charging double for every one of their bottles. As we left, our host insisted that we take a free corkscrew, just in case it was needed on the road. We motor on to Shottesbrooke, where a simple tasting extends into over an hour of easy and unaffected conversation that ranged from wine to university to travel to love to loss, and back to wine again.

I'm back home now, but I've brought them with me. When I open the Geoff Merrill 2000 cab sav (for $12.50! Unbelievable!), I'll remember the soft morning under the vines there. When the time comes for the divine Eliza Shiraz from Shottesbrooke to be liberated, it wont be without the memory of Mary's laugh on that wonderful afternoon in McLaren Vale. And it'll be all the better for it.

TypePad hacks: Display multiple random entries

Please excuse me while I geek out for a moment. I've added a feature to the individual entry pages of this site that displays links to 5 random posts from the archives. It requires a bit of a workaround for TypePad, a work around that I spent a while searching for. This won't apply to the majority of you, but I'm posting it here to save the next person a bit of time.

The hows and whys are after the jump.