I saw a sign the other day outside one of those Chinese-Japanese hybrids that are beginning to pop up around town, advertising 'Discount Sushi'. I can't imagine a better example of Things To Be Wary Of in the food department than bargain sushi.

I never order fish on Monday, unless I'm eating at a four-star restaurant where I know they are buying their fish directly from the source. I know how old most seafood is on Monday - about four to five days old!

I don't eat mussels in restaurants unless I know the chef, or have seen, with my own eyes, how they store and hold their mussels for service. I love mussels. But, in my experience, most cooks are less than scrupulous in their handling of them. It takes only a single bad mussel, one treacherous little guy hidden among an otherwise impeccable group ... If I'm hungry for mussels, I'll pick the good-looking ones out of your order.

Brunch menus are an open invitation to the cost-conscious chef, a dumping ground for the odd bits left over from Friday and Saturday nights. How about hollandaise sauce? Not for me. Bacteria love hollandaise. And nobody I know has ever made hollandaise to order. And how long has that Canadian bacon been festering in the walk-in? Remember, brunch is only served once a week - on the weekends. Cooks hate brunch. Brunch is punishment block for the B-Team cooks, or where the farm team of recent dishwashers learn their chops.

I won't eat in a restaurant with filthy bathrooms. This isn't a hard call. They let you see the bathrooms. If the restaurant can't be bothered to replace the puck in the urinal or keep the toilets and floors clean, then just imagine what their refrigeration and work spaces look like.

Beef Parmentier? Shepherd's pie? Chilli special? Sounds like leftovers to me. How about swordfish? I like it fine. But my seafood purveyor, when he goes out to dinner, won't eat it. He's seen too many of those 3ft-long parasitic worms that riddle the fish's flesh. You see a few of these babies - and we all do - and you won't be tucking into swordfish anytime soon.

'Saving for well-done' is a time-honoured tradition dating back to cuisine's earliest days. What happens when the chef finds a tough, slightly skanky end-cut of sirloin that's been pushed repeatedly to the back of the pile? He can throw it out, but that's a total loss. He can feed it to the family, which is the same as throwing it out. Or he can 'save for well-done': serve it to some rube who prefers his meat or fish incinerated into a flavourless, leathery hunk of carbon.

Vegetarians, and their Hezbollah-like splinter-faction, the vegans, are a persistent irritant to any chef worth a damn. To me, life without veal stock, pork fat, sausage, organ meat, demi-glace or even stinky cheese is a life not worth living. Vegetarians are an affront to all I stand for, the pure enjoyment of food. Oh, I'll accommodate them, I'll rummage around for something to feed them. Fourteen dollars for a few slices of grilled eggplant (aubergine) and zucchini (courgette) suits my food cost fine.

Secrets of the chef's kitchen for a home cook

You need, for God's sake, a decent chef's knife. ONE good chef's knife, as large as is comfortable for your hand. Like a pro, you should use the tip of the knife for the small stuff, the area nearer the heel for the larger.

The indispensable object in most chefs' shtick is the simple plastic squeeze bottle, essentially the same objects you see at hot-dog stands loaded with mustard. Mask a bottom of a plate with, say, an emulsified butter sauce, then run a couple of concentric rings of darker sauce - demi-glace, or roast pepper purée - around the plate. Now drag a toothpick through the rings or lines.

Gaufrette wha'? That's French for waffle-cut. You can do that. All you need is a mandolin, a vertically held slicer with various blade settings. Dauphinois potatoes cut to identical thickness? No sweat. You didn't think they actually cut those with a knife, did you?

Let me stress: heavyweight pans. A thin- bottomed saucepan is useless for anything.

Ingredients that mark out restaurant food:

Shallots

Essential for sauces, dressings, sautés.

Butter

In a professional kitchen, we sauté in a mixture of butter and oil for that nice brown, caramelised colour, and we finish nearly every sauce with it (we call this monter au beurre); that's why my sauce tastes creamier and mellower than yours. Margarine? That's not food. I Can't Believe It's Not Butter? I can.

Roasted garlic

Garlic is divine. Misuse of garlic is a crime. Old garlic, burnt garlic, garlic cut too long ago, garlic that has been smashed through one of those abominations, the garlic press, are all disgusting. Sliver it for pasta, like you saw in Goodfellas. Smash it with the flat of your knife blade. And try roasting garlic. It gets mellow and sweeter if you roast it whole, to be squeezed out later when it's soft and brown.

Chiffonaded parsley

Restaurants garnish their food. Why shouldn't you? Dip the sprigs in cold water, shake off excess, allow to dry for a few minutes, and slice the stuff, as thinly as you can, with that sexy new chef's knife.

Stock

The backbone of good cooking. Roast some bones, roast some vegetables, put them in a big pot with water and reduce, reduce, reduce. Make a lot, and freeze it in small containers.

Demi-glace

Simply take your reduced meat stock, add some red wine, toss in some shallots and fresh thyme and a bayleaf and peppercorns, and slowly, slowly simmer it and reduce it again until it coats a spoon. Strain. Freeze this stuff in an ice-cube tray, pop out a cube or two as needed, and you can rule the world.

Fresh herbs

A nice sprig of chervil on your chicken breast? A basil top decorating your pasta? A few artfully scattered chive sticks over your fish? A mint top nestled in a dollop of whipped cream, maybe rubbing up against a single raspberry? Come on! Get in the game!

Good food is often simple food. Some of the best cuisine in the world - whole roasted fish, Tuscan-style, for instance - is a matter of three or four ingredients. Just make sure they're good ingredients, fresh ingredients, and then garnish them.

Example: here's a dish I used to serve at a highly-regarded two-star joint in New York. I got 32 bucks an order for it and could barely keep enough in stock, people liked it so much.

Take one fish - a red snapper, striped bass, or dorade - have your fish guy remove gills, guts and scales and wash in cold water. Rub inside and out with kosher salt and crushed black pepper. Jam a clove of garlic, a slice of lemon and a few sprigs of fresh herb - say, rosemary and thyme - into the cavity where the guts used to be. Place on a lightly oiled pan or foil and throw the fish into a very hot oven. Roast till crispy and cooked through. Drizzle a little basil oil over the plate - you know, the stuff you made with your blender and put in your new plastic squeeze bottle? - sprinkle with chiffonaded parsley, garnish with basil... See?

© Anthony Bourdain, 2000

• This is an edited extract from Kitchen Confidential: Adventures In The Culinary Underbelly by Anthony Bourdain (Bloomsbury £16.99). Buy it from the Guardian bookshop