Vegetables, you might think, are simple enough things to cook. Now that we've escaped the dread clutches of Mrs Beeton and her 45-minute carrots, there's not much left to learn. After all, just how much culinary mystique can a marrow deliver?

Well, you may be surprised. Marrows, according to Elizabeth David, who delivered such a scolding last week on the subject of the garlic press, "should be prepared for cooking in the same way as aubergines; cut, preferably unpeeled, into rounds or lengthwise, salted, and left to drain for an hour or so." What a lot of fuss for an overgrown courgette.

Now, I regret to admit I don't have much to do with the marrow (my boyfriend hates the things, however cunningly disguised as meat), but I haven't pre-salted an aubergine in years. After all, that would necessitate beginning prep an hour and a half before I wanted to eat, which is usually about the time I'm rushing around the shops grabbing the ingredients for dinner. It just wouldn't work. But is this mere culinary laziness, akin to using teabags or leaving the skin on carrots (more nutritious, I tell myself) – or is the tradition a genuine waste of time and salt?

I'm comforted to learn that Nigel Slater, who is a cook after my own heart (he knows the odd jar of shop-bought pesto isn't the end of the world), never troubles himself with it: he claims not to have tasted a bitter aubergine in years. Larousse Gastronomique concurs: "Traditionally, the slightly bitter taste of the vegetable was minimised by sprinkling the sliced or cut-up flesh with salt and leaving it for 30 minutes to draw out the bitter juices. The aubergine was then rinsed and dried before cooking. The process of degorging is no longer necessary as commercially cultivated aubergines are not as bitter as they used to be."

That should, in theory, be that. The bitterness has been bred out of aubergines since Elizabeth David first introduced this magnificent vegetable (which, to pre-empt all you pedants, is strictly speaking a fruit) to this country, so they no longer require salting. Except that, just to confuse the issue, Hugh Fearnley-Whittingstall claims that, although degorgement (as it seems to be somewhat saucily known) won't make any difference to the flavour, it will stop the aubergine soaking up as much oil as you can throw at it during cooking.

Delia also salts – but for different reasons: "I do take the point that the modern aubergine has evolved to a state where it does not contain bitter juices," she says reasonably, "but the juices are there, nonetheless, and I find salting and draining gets rid of excess moisture and concentrates the flavour – there's nothing worse than a watery aubergine." Even Skye Gyngell, who, as head chef at the delectable Petersham Nurseries, should know a thing or two about vegetables, is in favour of salting. So who's right?

Salted aubergines with drained juice. Photograph: Felicity Cloake

Two plump aubergines, of roughly the same size and glossy firmness, should settle the matter. I decide to follow Elizabeth David's instructions for a Sauté of Aubergines, as that's the simplest recipe I can find, leaving out the garlic and parsley, so as not to overpower their delicate flavour. One aubergine is diced, sprinkled with salt, and left for an hour as instructed. I'm surprised to discover, on my return, that it's produced a tablespoon and a half of rusty-coloured liquid, which tastes more like seawater than anything bitter.

I chop the other into equally sized pieces, and heat two heavy-based pans with "a good quantity of olive oil" (a couple of tablespoons), then fry them both "rather gently, turning them over from time to time" for 15 minutes. Although the non-salted batch soaks up the oil more rapidly, both pans are equally dry by the end. And the results? I can detect no greater intensity of aubergine flavour in the salted batch – in fact, it just tastes saltier. (David didn't tell me to rinse the salted aubergines before cooking, and, to be fair, Delia or Skye don't either.) The texture of both aubergines, as far as I can tell, is almost exactly the same: neither greasier, nor more watery. So, if it makes so little difference to the oil consumption when frying, I'm not inclined to take up salting again, particularly as I usually grill or bake the things.

Unsalted (l) and salted (r) aubergine pieces after shallow frying. Photograph: Felicity Cloake

Perhaps it's fair enough that we're a bit clueless about aubergines – after all, we haven't been eating them very long. But to be peddling myths about good old brussels sprouts is inexcusable. Step forward, Nigella Lawson, Raymond Blanc and Skye Gyngell: all guilty of advising people to cut a cross in the base of their sprouts to help them cook more evenly.

Hugh, Gordon and the chairman of the Brassica Growers Association, Philip Effingham, are all against the cross on the grounds that it turns the unfortunate vegetables to mush – heck, even Delia's changed her mind since publishing her Complete Cookery Course back in the 1980s, now reassuring the public that there's "no need to make incisions in the stalks".

The thinking behind the cross myth seems to have been to encourage the inside of the sprout to cook more quickly, before the outer leaves disintegrated: a particular problem in the past, when those on sale tended to be larger than they are now. Unfortunately, as recent convert Nigel Slater has observed, whatever the size of the sprout, cutting into them in this way just leaves them waterlogged and soggy. But many Word of Mouthers disagree – quite vocally, as we discovered before Christmas. So I decided to try out the cross again, just in case.

The first thing I noticed was that anointing each sprout with a festive cross, which I had always viewed as a faff, even before deciding it was pointless, is actually not that much trouble. Peeling off those tight outer leaves is much more time-consuming: the cross is the easy bit. The second batch of sprouts, peeled and tailed, but with no cross, took about as long to prepare as the first. I then boiled both lots for six minutes.

Sprouts uncrossed (l) and crossed with a knife before cooking (r). Photograph: Felicity Cloake

The carefully-crossed sprouts brought back memories of canteen Christmas dinners past – yellowing and faintly sulphurous on the outside and slightly pappy at the core, with a ring of bouncy, undercooked flesh in-between. The non-crossed ones were simply overcooked on the outside, and chewy in the middle. Neither were satisfactory examples of this mighty vegetable, which is why I generally cut mine in half, so they're ready before the outer leaves can turn nasty, and remain appetisingly green to boot. I don't often say this, but I'm with Gordon on this one.

What do you think – are salting and crossing a waste of time, or am I missing something? And if you agree, have you got any better advice for stopping your aubergines swimming in oil, or cooking the perfect sprouts?