Pesto is a generic Italian name for any sauce made by pounding ingredients together.
The best known of these is pesto Genovese, usually shortened in the UK to just pesto. This is based originally on handfuls of the bright and bold basil grown around Genoa, pounded together with pine nuts, garlic (only a little) and olive oil and then finished with finely grated Parmesan and pecorino (sheep milk) cheeses.
Pounding in a pestle and mortar releases the pungent oils of the basil in a way that chopping or whizzing in a food processor cannot replicate, even though the results are very tasty.
Homemade in high summer is best, by far. Bought pesto Genovese has, inevitably, been pasteurised and thus the freshness has been compromised; to right this, pound fresh basil leaves and add them to the mixture.
Choose the best
When starting from scratch with basil, ensure the picked leaves are truly fragrant and resinous with a definite lemony/citric bite and a clear aniseed/liquorice undertone. If they seem just green and a little acidic, you won’t get a good result, no matter how much you use. Different basil varieties, such as the more pungent Holy Basil, can be used, especially if the sauce is to go with meat or fish.
These days, commercial pestos are being made with almost anything Mediterranean, including sun-dried tomatoes, olives, almonds and many other nuts, lemon and orange zest, and with such different herbs as coriander, parsley and rosemary.
Homemade will last for days but the flavour balance changes and the garlic and cheeses will dominate the basil. Store-bought pesto sauces will last longer and this is often due to preservative ingredients. These can be enlivened by adding a fresh version of the main original ingredients, like basil, coriander leaf, olives or sun-dried tomatoes.
When cooking with pesto Genovese, remember that the flavour of fresh basil is fugitive when heated; it’s better to add the sauce at the last moment, as with the epitome of pesto eating, piled high onto freshly cooked pasta, where the heat will increase the heady fragrance of the basil without defeating it.
Grilled vegetables all seem brighter with pesto Genovese. Fish enjoys a dollop of pesto Genovese, as does chicken and lamb and, although you can use it as a stuffing for any of these, using it fresh as a condiment will be more memorable. Pesto rather than parsley in the aspic for cubed ham, chicken or salmon will make any picnic or al fresco event a triumph.
Pioneering BBC-TV Chef Glynn Christian is author of REAL FLAVOURS - the Handbook of Gourmet and Deli Ingredients, voted 'World's Best Food Guide'.