This is pretty much where it started for Jennifer McLagan, the ex-Melburnian who lives in Canada and has made a career out of writing food books that challenge. Her first was Bones. Then Fat (which she loves, and celebrates as highly healthy). Now it's Odd Bits, a book that plunges in glorious detail and marvellous straight talking right into the midst of spleens, stomachs and intestines, gizzards brains, lungs, feet, cheeks and ears - a list that makes you think of an adult version of that childhood ditty - head, shoulders, knees and toes.

There is a dare factor, McLagan recognises, in the growing interest in the lesser cuts. But the people who eat confronting bits for the thrill of the weird are only part of the picture. For people like McLagan herself, it's about respecting the animal, not wasting tasty food, and simply doing things the way her parents did.

''As a child, I ate a lot of odd bits,'' she writes in her book. ''My mother made wonderful soups from bones and hocks, unctuous oxtail stew, and homemade meat pies filled with a palatable mixture of odd bits. I sucked the marrow from bones and ate ox tongue set in wobbly jelly every Christmas.''

It wasn't all good, though. Tripe (stomach) in white sauce, and crumbed lamb's brains, she remembers with anything but fondness. Totally disgusting, McLagan writes. ''I wasn't put off by any strong gutty odour or pungent flavour, but rather by the complete absence of both odour and flavour, and the odd, chewy, congealed texture of it all.''

The Sunday-night brains were no better, and McLagan says her habit was to eat the breadcrumb coating, then slip the brains into her dressing gown pocket to throw out later.

Her distaste will be familiar to many, but fewer will have had a conversion quite as complete as McLagan, who now counts the throwaway cuts of meat as among her favourites. She had her tripe epiphany in France at the family home of a child she tutored, when she ate tripe - finding it rich, pleasantly chewy, slightly slippery and gelatinous - before knowing what it was. It was the beginning of a journey that took her into headcheese, intestines, pig's feet and blood sauce, all the way to brains - which she didn't try until much later, thanks to a chef friend in Toronto. Light, crisp, rich and creamy in the centre, she says, declaring brains delicious.

''It's a moral issue when it comes down to it,'' McLagan says in a telephone interview, quoting London's Fergus Henderson as saying, ''if you knock an animal on the head its only polite to eat all of it''.

''We can raise an animal well and slaughter it quickly, but the most respect we can show is to use all of it and not waste any of it,'' McLagan says.

People have short memories on the topic, she says, pointing out that British menus were full of offal just a few decades ago. Hugely influential US cookbook The Joy of Cooking even has a recipe from the 1980s for cockscombs.

Cockscombs? Why would we eat cockscombs? Their shape makes them a fabulous garnish, McLagan responds, and they are very gelatinous. They're a bit fiddly. You need to soak them in salted water for a few hours to remove any blood, then blanch, then rub off the membrane that covers them, using a towel and coarse salt to help. Then cook them slowly and they take on the flavour of their cooking liquid. It doesn't need to be savoury. McLagan recalls eating cockscombs as dessert in Montreal, where they had been simmered in blood-orange juice, and tasted, she says, like an orange jellybean.

This slow and patient handling is a feature not only of cockscombs but of a number of odd bits. Take chicken feet, for which McLagan would have you use kitchen scissors to cut off their nails, then ''if there are any hard or rough pieces of scaly outer skin, hold them over a gas flame or use a propane torch to blister and loosen the pieces and then rub them off with a towel''.

Pig's ears also require patient work. First, singe or shave off any hair, and clean them thoroughly inside, then salt them for two days before poaching them for a couple of hours in a court bouillon, then flatten them, by weighing them down in the fridge overnight. Finally, you're ready to roast or grill them, or just use as is, sliced in a salad. Ears make up for lack of meat, she says, with crisp or chewy skin (depending how you cook them) and with crunchy cartilage.

Similarly with tongue, a staple of McLagan's childhood Christmases. Brining for a couple of days first will improve the flavour. Then you need to poach it (in a stock of onion, carrot, celery, spices and herbs), then you must skin it while it's still hot. McLagan has detailed instructions for this, and it has to be said, peeling a tongue sounds like an acquired skill. The world of tongues is vast, all the way down to tiny duck tongues, but McLagan suggests beef tongue as the most simple, since it's bigger, so less peeling. She has an intriguing recipe for tongue stewed with chillies and spices, Mexican style, and served with lime and coriander wrapped in tortillas. ''It will convert even the most sceptical to the delights of the tongue,'' she declares. But if you're an old hand at this kind of thing, you can go further and make the dish with tripe or chitterlings.

To this reader, chitterlings are one of the more confronting animal parts McLagan champions. Chitterlings are intestines, not the kind you use as casings for sausages, but intestines with the pink mucus lining still in. This lining - the mesentery - holds chitterlings together and gives them their flavour. Which means you can eat them as a dish in their own right. They vary in taste from earthy and gutty to mild, and in texture from chewy to very tender, depending on how they have been cleaned and cooked. And they can be very good, she insists, recounting buying chitterlings in Box Hill, a Melbourne suburb with a big Asian population, and cooking them in tomato sauce for a friend ''who was a little appalled, but when she tasted them she was like wow these are really tasty''. The French sausages andouille and andouillette are made from intestines that are stuffed with intestines - and in the case of andouillette also stuffed with other bits like pork belly and mesentery. They smell stronger than they taste, McLagan says, but like Munster cheese and white truffles, the smell is part of the experience.

McLagan deals with such details in such a reassuring tone and with such clear affection - to her, heart liver, spleen, kidneys, stomach, intestines and caul fat are no less than an ''exotic treasure trove'' - that it's easy to lose sight of the fact that she's dealing with what to many people are the most difficult parts of the animal to eat. She does acknowledge the challenge: ''The truth is that some parts, while tasty, have very challenging textures,'' she concedes.

But she puts much of our distaste at odd bits down to cultural differences. What's unusual in one culture is everyday in another. She's not big on insects, she says by way of example, but recognises that oysters are eaten alive, as are witchetty grubs. ''So it's in my head, too, there's a cultural thing in your head. Some things are much more challenging than others to eat just because you're unfamiliar with them.''