Vegetables are blanched for several different reasons: mostly either to part-cook because the ultimate cooking technique would otherwise take too long (or fail) to make them tender, or to cook the vegetables ahead.
Certain vegetables definitely benefit from a brief blanching process before being incorporated into dishes. For example, fine sliced leeks blanched for one minute, refreshed and then gently stewed with butter for 5 minutes are better than leeks cooked without the preliminary blanching. Large peas also benefit from the same procedure, though they need longer cooking in the butter. Also, should you be faced with the ghastly prospect of peeling pickling onions in large quantities, try blanching them for 60 seconds before refreshing and then peeling. This simplifies matters enormously and stops you crying.
The technique of blanching vegetables briefly in boiling salted water and then refreshing them in ice-old water to stop the cooking process is central to the mise en place in the professional kitchen. The vegetables are then held until needed in the fridge. All that needs to be done to bring those vegetables back to pristine, just-cooked perfection is to dip them again in boiling water for a few seconds. It is a technique which buys you time, keeps the hob dear and helps you get food on the table on time.
Most green vegetables and small root vegetables, like new season’s bunched carrots, are best cooked by blanching. The principle is to use lots of fast-boiling water which has been quite heavily salted. What does ‘heavily salted’ mean precisely? Like many chefs I am over-fond of salt and in an ever more nitrophobic world I am aware that this can cause problems. However, blanching involves a brief exposure to salt followed by a plunge in cold unsalted water to refresh which, coincidentally, removes much of the salt Salt impacts on the colour - keeping green vegetables green - and helps retain the nutrients. I would say, therefore, that salting at 1 tablespoon for every 1 litre / 1¾pt is about right.
Three-quarters fill the pan with cold water. Cover with a lid and bring to a fast, rolling boil (this is critically important as blanching is not poaching - it is a short and very fast process which preserves the freshness of the vegetables).
Put the vegetables into the basket and lower into the fast-boiling water for the requisite time. Do not cover.
When done, immediately remove the vegetables and plunge them straight into the bowl of cold water and leave until cold, then drain (do not leave in the water for too long as this leeches out flavour).
You can blanch up to 450g /1 lb of vegetables at a time. If you try more than this amount in one you go, you will lower the temperature of the boiling water sufficiently to slow the cooking process and this will cause the vegetables to lose colour and absorb too much salt.
© 1993 Alastair Little and Richard Whittington estate. All rights reserved.