Never ever dream of making this in a mortar and pestle. It’s incredibly tedious, and to my mind only succeeds in over-oxidising the basil, turning it an unattractive khaki colour. The quantity made here requires an enormous amount of basil, and I recommend you make it in summer when it is relatively cheap. You will also need a couple of clean screw-top jars to keep it in. The best way of sterilising a jar these days is to run it through a dishwasher at high heat.
Combine the pine nuts, Parmesan and garlic in the food processor, and chop to a coarse meal. Season with salt and pepper. Fill the food processor with the basil, chop for a few seconds, then remove the lid and stir the ingredients. Replace the lid and continue chopping. Pour in enough olive oil to form a stiff paste. Taste for seasoning. It may need more olive oil. I cannot give a precise quantity of olive oil, but it’s probably in the region of 300 ml.
Working quite quickly, as the mixture tends to discolour rapidly – at the moment it will be a bright green and filling your kitchen with the wonderful scent of summer – pack into your prepared jars. Tap the jars lightly when full on a folded teatowel; this will drive any bubbles of air to the top. Using a rubber spatula or the back of a clean spoon, press the pesto surface flat. Pour in enough olive oil to cover it completely. Seal the jars and refrigerate until needed.
The pesto will keep unopened for a considerable time in your fridge. Once you open it, you only have 2–3 days. Remember each time you use it to smooth down the surface and re-oil. This will prolong its shelf life.
Should you be lucky enough to find aged Pecorino (a sheep’s milk cheese), it can be substituted for Parmesan, making the whole thing much more authentic.
© 1996 Alastair Little. All rights reserved.