But the argument between the pure and the mixed is at its most contentious in vegetables. We have long accustomed ourselves to certain combinations: the plate of crudites and, above all, the mixed salad, into which almost anything can go. Similarly, ratatouille, with its potent blend of strongly flavoured vegetables, has become a sort of modern summer demonstration of a plentiful harvest.
On the other hand, many people believe there is something incomparable about isolating the particular virtues of a single vegetable and bringing that one taste out in whatever manner does it best. I admit that a perfect green bean, cooked with care, is a thing of beauty. Just about the only enhancement it needs is absolutely fresh butter, and a tiny touch of garlic and fresh salt. The lack of that perfect butter is, of course, why it often does not work, especially in restaurants. A bean 'revived' in the pan after straining, in semi-rancid, low-grade, salty butter, is an insult.
In general, a garden-fresh vegetable is most delectable on its own: who would fiddle (beyond a little butter) with a luscious Breton artichoke in season? What is better than a beetroot served in its simplest form? Or sweetcorn? I am such a purist on this score that when I find a fresh and superb potato to bake, I disdain to add anything but a little salt.
Consider those vegetable combinations to which we are all accustomed. Fresh, sweet peas need little more than butter and salt (as an old pea-sheller I eat quantities of them raw), but a few lettuce leaves added to their slow simmering does wonders. There are intrinsic affinities in the vegetable kingdom, such as tomatoes and peppers, or tomatoes and aubergine. Little spring turnips solo are a wonder; when lightly sauteed with a few slices of sweet white onion they are a dish for the gods. Certain white vegetables such as cauliflower benefit from accompanying flavours; they are surprisingly good with separately fried green peppers, as long as the latter are used sparingly.
As I found out in China, almost any vegetable may be affixed with another. This is largely a matter of taking into account the cooking time of different vegetables to make them all come together at the same moment. The ubiquitous mangetout does not, in my opinion, fare particularly well in this regime, nor do the many members of the squash family, which tend to disintegrate. A vegetable has to be sturdy to survive in a wok.
In southern France, where I am enjoying my sabbatical, the prevailing flavours, as one might expect, are the local products: olive oil and olives in general, garlic and anchovies. These, in various combinations (sometimes with wine), form a velvety base in which much local cooking, including vegetables, takes place. Oil and garlic, yes, you will say: but anchovy?
Well, if you can lay your hands on fresh anchovies (or if you can find whole ones salted and are willing to go through the long process of desalinating them), that base is a wonderful one for bringing out the flavour of the richer, stronger vegetables, and even of the weaker ones in combination.
The lady who cleans our house unfortunately threw away a recipe for bagna cauda, basically a vegetable fondue, that I had preserved; but I can remember enough to offer my own interpretation. Assuming you have a fondue pot or anything else you can keep bubbling on the table, I urge you to try it. You may not get it right first time, but you may also discover something along the way.
Prepare a sufficient quantity of oil, lightly flavoured with garlic, in which you have macerated a good number of anchovies (filleted). Prepare two piles of ultra-fresh vegetables: one that you will steam until they have lost their hardness, but not to the point of being edible (cauliflower, carrots, peppers, sweet onions); and the other consisting of vegetables that will cook in hot oil within a minute (sliced fennel, diced aubergine and almost any leaf vegetable).
Season with coarse salt and pepper. Skewer them on brochettes with a little onion between for the bottom two or three inches only. Get the oil-and-anchovy mix to the appropriate temperature (as high as you can without smoking), stirring so the anchovy permeates the oil, and cook the vegetables by dipping into the hot oil. Time-consuming to prepare, yes; but the cooking is quick. Result: a bouquet of vegetables blended by a common flavour.