Walnut and other nut oils

The Anglo-Saxon world, or at least the representatives of it who node here on E2, seem to believe that French people cook exclusively with "extra virgin olive oil". Nothing could be further from the truth.

While olive oil does play a prominent role in French cuisine, the actual production of olive oil in France is so small that many parts of the country do not use it in regional dishes. Olive trees grow commercially only in the Mediterranean coastal areas. Nyons, on the Eygues River in the Drome, is the most northerly center of production.

Cooking with oil in traditional French fare was limited to the south and in mountainous regions such as the Perigord and the Alpine departments. The south, mainly Provence, used olive oil. The others used nut and grain oils. The four most common grain oils used today are derived from corn (maize), sunflower seed (tournasol), rape seed (colza)1 and grape seed (pépin de raisin). The last two, being very neutral in flavor, are often mixed with other strongly-flavored and more expensive oils.

The nut oils are particularly interesting because of their various flavors. Most of them are delicate and cannot be used for frying; some do not support heat in any form and are always used cold. Here are the nut oils commonly used in France today.

Almond - Mild and perfumed, it is used principally in marinades (salmon) or on shellfish, fruits and pasta after the dish is cooked.

Hazelnut - Smooth and lightly perfumed, it is favored for salads but is also used instead of butter on starches (potato and rice), cooked vegetables (asparagus, green beans), or raw vegetables (grated carrots).

Peanut - Although not produced in France, it is very popular, possibly as a result of so many French expatriates acquiring a taste for it while living in the ex-French colonies of Africa. It is often used in cheese-based recipes which is odd as cheese is not a common food in West and Central Africa.

Pecan - A pronounced flavor, falling between that of walnut and almond. It is used mainly with rice dishes and to flavor cakes and other pastries.

Pine Nut - One of the most subtle in flavor, it is used mainly to enhance other flavors. It is added at the last minute to cooked wine sauces and soups such as minestrone. Considered indispensable in pesto.

Pistachio - With a very prominent taste and a persistent aroma, it does not mix well with all vinegars for a salad dressing. It is best used with balsamic vinegar.

Walnut - This is the star of the nut oils and the most widely used. Less than a score of years ago it was considered the "grease of the poor"; today it commands very respectable prices in fancy boutiques.

The Greeks used walnuts and walnut oil 4 centuries before Jesus Christ and the Romans made the culture of the walnut tree popular in all of Western Europe. Having a low fat content, it was sometimes used for oil lamps. It does not support heat and, in a pure form, does not keep well even if in a sealed container. It is at its best between January and March following the nut harvest.

It takes six kilos of walnuts in the shell to produce one litre of oil. Unlike the grain and many olive oils, it is generally produced artisanly rather than in a refinery. Like olive oil, the best quality is "virgin cold pressed". This is when the nuts are ground into a fine paste and the resultant oil bottled. This paste can then be very gently heated to extract more oil which is called "virgin" as it comes from the first grinding but "cold pressed" is omitted on the label. The next grade down is "l'huile fruitée de noix", or "walnut-flavored" oil. Generally rape seed oil (canola) is mixed with walnut oil to produce this. Most of the walnut oil sold in European supermarkets is of this quality. The final grade is "walnut impregnated" oil for which walnut meats are grilled and then soaked in rape seed oil. This last should be used only for seasoning (as in salad dressings) because the walnut flavor, having been once heated, will disappear with a second exposure to heat.

If you have never tried walnut oil, I suggest you first make a vinaigrette (recipe below), substituting macadamia nut oil for walnut oil to see if you really want to buy an entire bottle of it. Walnut oil is very fragile and turns rancid quickly. It is best to purchase it in small amounts, to keep it in the refrigerator after opening, and to immediately replace the cap after use as exposure to air quickens the onset of rancidity.

The following vinaigrette can be kept up to twelve days in a well-closed bottle in the refrigerator. It calls for one level teaspoon of sharp mustard, 1-1/2 level teaspoons of table salt, and a pinch of white pepper. The vinegar (16 fl. oz./500 ml. total) is half red wine and half balsamic. The oil is half the amount of the vinegar (8 fl. oz. or 250 ml.), being a mixture of 2/3 canola (rape seed) and 1/3 walnut oil. Whisk in the usual fashion and add 2 fl. oz./60 ml. of warm water at the end.

Another salad dressing using walnut oil is "Sauce Roquefort aux Noix" and uses crumbled Roquefort cheese, walnut oil, light cream and a bit of cognac. This is often served on a salad of mixed greens which also includes coarsely chopped walnut meats and tiny cubes of fried salt pork (lardons grillés).

The vinaigrette described above is very good on a salad made of white beans. Use canned white beans for a quick salad, but it is better to cook dried beans which have first been soaked and then boiled with a clove of garlic and an onion pricked with three cloves. After the beans are cooked and drained, toss with the vinaigrette while they are still warm. This ensures that the flavor will impregnate the beans and will also avoid an excess of oil. Once the beans have cooled, add sliced tomatoes and chopped dill pickles.

Salade de mâche et foie de veau aux 3 huiles. This one is on its way to being a classic. "Mâche" is a soft but pungent small-leaved green, otherwise known as "lamb's lettuce". Walnut oil goes very well with bitter things and is often used on endive, dandelion, and chicory, so this member of the mustard family is perfect. Here's the recipe for :

Watercress with veal liver and three oils (for 4 people)

10 oz./300g of lamb's lettuce
10 oz./300 grams of veal liver
20 sprigs of parsley
50 walnut halves
16 cherry tomatoes
1 tablespoon of walnut oil
1 tablespoon of canola oil
1 teaspoon of olive oil
Balsamic vinegar, salt and pepper

Clean the greens, quarter the tomatoes, mince the parsley and chop the walnuts. Cut the liver in half-inch cubes.

Put the greens in a salad bowl, sprinkle with the walnut and the canola oil and toss well. Add the tomatoes and the walnut meats. Heat the olive oil in a skillet and quickly and lightly brown the cubes of veal liver. Add the parsley and remove from the heat. Put this in the salad bowl on top of everything else. Now take the vinegar and splash a bit into the skillet, return the skillet to the heat for 30 seconds, scraping the bottom of the pan with a wooden spoon. Put this "skillet juice" on the salad, mix well and serve at once.

Finally, one more dish that may have more appeal to non-French readers.

Gratin dauphinois à l’Isère. The recipe is basically scalloped potatoes (gratin dauphinois) made with butter and cream. Use only potatoes, butter, cream, and salt. The flavor is provided by the walnut oil. Use a waxy potato and cut as thin as possible. If I am making a small quantity (say for less than 6 people), I will shave the potatoes with a floating-handle potato peeler. This gives slices you can read a newspaper through. Rub the bottom of the dish with a sliced garlic clove before you put the potatoes in, and add a pinch of cinnamon to the cream before pouring it over the potatoes. Use a large, shallow dish rather than a small, deep one. After it is cooked, run this under the grill for 3 to 5 minutes. Just before serving, dribble half a cup or so of walnut oil over the entire surface. Beautiful. The best I ever ate was in a little truck stop at the very top of a mountain pass just south of Grenoble one cold and blustery November day.

1Rape seed oil is known as huile de colza in France and as "canola oil" in the U.S. Produced in Canada, "canola" is an acronym. Colza appeared in the French language in the mid-1600's and is Dutch in origin, meaning cabbage (kool) seed (zaad). Tourists in France today, seeing fields of yellow flowers, think they are looking at a crop of mustard but more often than not it is colza.