Chewing fat Fat isn't considered by most people to be a seasoning, and that's correct when it comes to the neutral-tasting oils called for so frequently in recipes. Often you don't want the taste of the fat to intrude: when making truffle oil, for instance, you want the pure flavour of the tuber, so you would infuse it in grapeseed or canola oil.
Other times, though, you can use the distinct flavours of certain fats to enrich a dish. Potatoes sautéed in duck fat, for example, have a much richer flavour than those cooked with canola oil; and if you dress a salad with a vinaigrette made with hazelnut oil, it will taste very different from one made with extra-virgin olive. You can also (although I wouldn't advise it) make cakes with margarine or shortening instead of butter - these three solid fats have a similar effect on the texture, but the cake wouldn't be nearly as delicious without the latter.
You don't have to use fat sparingly; for pound cakes the same amount of butter is used as egg, flour and sugar; confit sees the meat poached in rendered duck or goose fat; and for vinaigrettes, traditionally, the oil used amounts to three or four times the volume of the acidic element.
Other times, though, just a few drops of flavourful fat are enough. If you use too much lavender oil, the dish will taste like perfume. You can "finish" a dish with fat, just as you might add a sprinkling of rough-flaked salt before serving: melt a pat of butter into a sauce just before pouring it over the meat, or drizzle an assertive-tasting olive oil over sliced, ripe tomatoes, before mixing them with mozzarella and basil.
It's easy to make your own seasoned oils: gently heat dried chillies, crushed peppercorns (a variety of colours is nice) or other spices (or spice blends) in peanut, canola or grapeseed oil, then leave at room temperature for a few hours, so the aromatics have time to infuse into the oil. Serve these spiced oils with bread or drizzle them over cooked meats just before serving.