Like vinaigrette, mayonnaise or hollandaise, pesto is a sauce you ought to be able to sling together on autopilot. The traditional Genoese version demands a lot of patient pounding with a large mortar and pestle, so use an electric blender instead to produce a vibrant, versatile paste in just seconds. The quantities below are approximate and the ingredients are open to variation: omit the parmesan, for example, to make it vegan; or replace the basil with rocket and the pinenuts with toasted walnuts. I sometimes add a dash of vinegar or lemon juice to inject some sharpness, though the acid will end up dulling the green colour if you then keep it for later use.
60g (two supermarket packs) fresh basil, thickest stalks removed
50 parmesan, grated
2 cloves garlic, crushed
120ml olive oil
Salt and pepper
If you have time, toast the pine nuts in a frying pan until lightly coloured or roast in a 180 (fan) oven for about 8 minutes (walnuts will take a little longer, maybe 10). Place in your blender with the basil, pinenuts, parmesan, garlic, salt and pepper, turn the motor on and pour in the olive oil in a stream until you have your desired consistency. Check seasoning and adjust as necessary.