From Chapter Eighteen, “Garnishes”, of English Cooking: A New Approach by Rupert Croft-Cooke (London, 1960), pp. 203-04:
How often in cooking, as in law and in life, one must go back to the word to understand. Perhaps because my trade is in words I exaggerate this but not in the matter of “garnish”. Many of enthusiastic ladies who write books about cookery have taken it that to “garnish” something means merely to decorate, it, and this has led to a lot of very odd goings on with flowers and inedible vegetable matter among which an honest fish may be found lurking as though under seaweed and anenomes in a rock pool. Isabella Beeton may have put paper frills on every available meet bone but she would never have called them a garnish.
The French verb garnir, from which we derive the culinary term, means to furnish, to provide, to stop as well as to ornament or adorn. The “house” that the Evil Spirit returned to, finding it “empty, swept and garnished”, did not have a Constance Spry flower arrangement in it; it was ready for its former occupant, without a tenant, cleaned and furnished.
The garniture of a dish is all that is served with it, preferably but not necessarily decorative. Roast beef is garnished with Yorkshire pudding and strictly speaking all the vegetables we eat with meat are garnishes for it, though we only use the word when they are arranged round it on the dish. Boiled beef is garnished with dumplings, cream soup with sippets, jugged hare with forcemeat balls and so on. So for most English dishes I have already discussed the garnish. But there remains something to be said on several of them and about certain decorations. It is important of course that food should look enticing and it is by garnishing a dish with flair and acumen rather than with rococo or sensational effects that this may be achieved.
It is not, for instance, good garnishing to paint over everything in sight with coloured gelatine, even if you call it aspic. Or to go mad with cold mashed potato and a rose icing pipe. Or to cut flower shapes out of raw turnips coloured with vegetable dyes. Or to put on a serving dish with food anything that, at least by conventional usage, could not be eaten or used with that food. You decorate a fish mayonnaise, perhaps, with a complete oval of thin slices of lemon, overlapping to form a garland. Nobody supposes that they will all be eaten but at least lemon “goes with” that fish and they are a legitimate garnish. If you surround it with fleurettes of raw cauliflower you are not garnishing but over-decorating. And so on. However attractive it can be made to look a garnish should be a natural accessory to the food it is with. How you decorate your table is another matter[,] though I’ve seen some pretty ghastly efforts here too. For if the serving -dish is the frame of your work of art the table is the wall against which it hangs and an elaborate wallpaper can make it almost impossible to see a delicate water-colour. The whole should be designed to set off the food and wine not compete with them.
Just as unforgivable is to sacrifice taste to appearance. At a professedly Old English Dinner in a hospitable home not long ago roast sirloin of beef with Yorkshire pudding was served. A vast salver was brought round with slices of Scotch beef deliciously underdone, garnished with watercress, potatoes roasted with the beef in the oven and little individual Yorkshire puddings made in patty pans. There is a metal for these pans, the cook proudly explained to me afterwards, in which anything can be baked without fact and without burning. It all looked very nice and was a convenient way of serving this food to the twelve of us at table. But of course it was not Yorkshire pudding which can only be cooked in the dripping from the joint.