A ‘pesto’ is simply a sauce, and there are as many ways to make it as there are cooks. In some parts of Italy – especially Liguria, where it originally comes from – it is only made with pecorino sardo, a delicious sharp ewe’s cheese. Parmesan wouldn’t even get a look in. Personally, what I’m serving it with influences how much of each ingredient I put into it. I love pesto with grilled fish, when I use a little less parmesan. For roast pumpkin I add more parmesan. I also love it thinned down with olive oil as a salad dressing, when I reduce the amount of garlic and add a little lemon juice. And so on. The following recipe will make enough for a good-sized jar of tasty pesto.