This expensive, delicate specialty oil is generally made in the Perigord and Burgundy regions of France, though there are also producers in Australia, New Zealand, and California. Wherever it is coming from, price usually is the determining factor in taste. Using whole nuts or large pieces, careful roasting, and proper filtering increases the price. Unlike other nut oils, unrefined walnut oil is made from nuts that are dried and then cold-pressed.
A good quality walnut oil is topaz in color with a rich nutty taste. Taking short cuts in the production process causes the taste of the oil to vary tremendously. Some producers simply macerate the nuts in vegetable oil. Others do not roast them after grinding. While others, for aesthetic reasons, over-filter to give a clear and pristine-look to the product. They all are doing the oil a disservice. Macerating gives little or no flavor to the oil; roasting is necessary for the rich nutty flavor (The label should always read that the nuts have been roasted), and too much filtering extracts too much flavor.
Walnut oil has a limited shelf life, about 6-12 months. Once opened, all nut oils should be kept in a cool place out of the light or refrigerated to prevent them from becoming rancid. But once you see how versatile it really is, I doubt it will sit around for long. Even the most ordinary of dishes will be transformed by its touch.
Walnut oil is not a cooking oil; high heat destroys its delicate flavor. Where it does shine is as an ingredient in a salad dressing or a fresh pasta sauce or to give a final splash over a finished dish.
How to use Walnut Oil
- Mixed with a little cream and medium dry sherry, it gives class to a piece of freshly poached salmon or chicken breast. A few toasted walnuts add texture and decoration.
- A mix of walnut oil, sherry vinegar, a touch of garlic, prepared mustard, and salt makes an excellent dressing for an endive and radicchio salad. Top the salad with a sprinkle of crumbled blue cheese.
- Walnut oil is a delicious alternative to olive oil in classic vinaigrettes or for dipping fresh bread. Either try it on its own, or with a splash of sherry vinegar, Cabernet Sauvignon vinegar or verjuice.
- Finish off a bowl of fresh sorrel soup with a drizzle of walnut oil.
- Walnut oil is fantastic tossed through pasta. With a soft blue cheese such as Gorgonzola, steamed fresh green beans or spinach, sautéed mushrooms or simply parsley and garlic.
- Use walnut oil to grease ramekins and moulds for desserts such as panna cotta. It will add a delicate, nutty dimension.
- For a festive breakfast or a Sunday brunch, try walnut and pear bruschetta (substitute bananas if you don’t have pears). Grill a thick slice of panettone, brioche or fruit bread, drizzle with walnut oil, top with slices of ripe pear, a few toasted walnuts and lashings of maple syrup, honey or chocolate sauce. Serve with thick Greek yogurt, whipped cream or mascarpone.
- Brush halved fruit such as peach or nectarine with a combination of walnut oil and honey before roasting or grilling, and serve with yoghurt or ice-cream.
- Goats’ cheese marinated in walnut oil is delicious with a salad and some crusty bread as a summer lunch. You can use the remaining oil for dressings or through pasta or potatoes.
- Lay 1cm slices of goats’ cheese in a dish and sprinkle with some fresh thyme, crushed garlic and freshly ground black pepper. Drizzle with walnut oil, cover and leave in a cool place to marinate for 24 hours. This is also good with a few chopped dried porcini mushrooms.
- In the winter, parsnips and Brussels sprouts taste great tossed with walnut oil before serving, or add some to mashed potato, carrot and parsnip.
- Brush walnut oil on fish, poultry and especially duck before grilling or pan frying. Or drizzle some around the plate before you serve.