At the sharp end: Lessons in slicing, dicing and mincing from a cutting connoisseur

Top chefs will often pay hundreds of pounds for the right kitchen knife. Will Coldwell visits the Japanese Knife Company to get a slice of the action.

Right, let's talk about knives!" Jay Patel claps his hands together excitedly before he unfurls a knife bag and unsheathes a glistening dagger. Standing in the Kensington branch of the Japanese Knife Company – a bountiful cornucopia of blades – I brace myself to get a slice of the action.

"There's no question that the knife was the most fundamental tool in creating, or at least changing, civilisation." Patel begins, "Together with fire and the wheel it is certainly one of the most influential tools that we ever had."

Patel is somewhat of an expert in the knife world. One of the only people outside of Japan to have trained as a blacksmith and also sell knives, he spent more than a decade there as an apprentice learning to forge, sharpen and use them after travelling to the country as a chef in the 1980s, returning to London to set up shop.

If this sounds like a long way to go to learn how to cut, then, like myself, you probably know very little about the world of professional cooking knives. However, under Patel's guidance I soon realise that there is a reason why a Saji Sujihiki, forged with 129 layers of Aogami Blue Steel, is worth £649, and why hacking away at a carrot with an Ikea breadknife is as much a waste of mental energy as it is physical.

In fact, without a good knife you would struggle to prepare food to the highest quality possible.

"A very sharp, thin blade won't actually influence the cell structure of the food", explains Patel. "If I cut my onion with a rough surface, it will tear the cells and it will lose its flavour. This goes all the way through all the food groups. If you cut fish and it looks like it's wet, that's the oil coming out – that's bad cutting. It should be absolutely bone dry, matt."

To demonstrate, he grabs an onion and within seconds has it minced into perfectly even, miniscule pieces. Scraping the pile into his hand he thrusts it up to my face: "See – no tears." Although my eyes do remain unwatery, his display of knife skills has me wincing as I remember the time I proudly discovered I could slice a pizza with scissors.

Patel reassures me: "Once you know how to use a knife you'll find you look forward to the preparation of food, not just the cooking and eating."

This is the precise sentiment of Peter Hertzmann, author of Knife Skills Illustrated, a book detailing the craft and history of knives, and, more specifically, how to use them. Currently Hertzmann, who teaches cooking in the US, has been training people from disadvantaged backgrounds, including inmates in jail, in knife skills – helping them to find employment in the catering industry.

"One of the excuses I've had for years as to why someone doesn't cook from home or from scratch, is that they don't know how to cut things up," Hertzmann tells me emphatically. "In less than two hours I can get someone well on their way to doing that, assuming they listen – some of the people I work with do have attention span problems..."

But Hertzmann commands my attention at least, asserting that good knife skills are key to encouraging people to enjoy cooking food. By extension, a good understanding of food preparation can be the difference between a healthy and unhealthy diet.

"For some of the women we teach it's not uncommon for her to be in jail with three to four kids. It's more a matter of training them how to prepare simple and healthy foods for their family. Feeling like you don't know how to do it at all tends to lead people into buying packaged things for the microwave. Even without a knife you could make a salad by tearing with your hands, but they're not even doing that."

This, I hope, is something I won't have to resort to, as back at the Japanese Knife Company, under Patel's supervision, I am becoming endowed with the art of slicing ("not chopping! You'll damage the blade!"), as I am guided through the three basic cuts: slicing, dicing and mincing. The knife I am using, sharpened before my eyes on Patel's own waterstone, barely needs an ounce of pressure to pierce the potato I'm pressing into the board.

I am using the most frequently used knife, a chef's knife. Despite the countless variations available, this, Patel says, is the one that deserves the most consideration. "Selecting a chef's knife should be done with a lot of care. If someone is really looking to buy a great knife, then they should see it like buying a tool".

Knife sets, it seems, are not the best investment. "When it comes to buying sets, if you are going to be doing 70-80 per cent of the work with one knife, this is the proportion of money you should spend on it. If you buy a block of knives then you'll get a boning knife in there – when was the last time you went out and boned something? People don't do that at home."

Hertzmann certainly agrees that massive knife sets are "over the top", just a way for manufacturers to sell more of their products: "When I go spend time in a professional kitchen I only take three knives with me.

"In Japan they use them quite differently to how we do in Western cuisine. If you watch them working on fish it's always done with a single slice. They've created a sort of religion around their knives and how you learn how to use them."

Michelin-starred sushi chef Yoshinori Ishii, head chef at London restaurant Umu, trained for 20 years in knife skills, and is, he tells me, still training. "When I was in culinary school, at 18 years old, I would be training after work until 2 or 3am, and I continued for one year like that. Back then I cut myself more than vegetables!"

He has about 12 knives to hand at any time. One, which is 60cm long, and weighs 700g, has only one role; cutting Conger eels. "For Japanese cooking, knives are one of the most important things." Ishii explains, "For sushi, or sashimi – one of the simplest cuisines in the world – you just cut the raw fish. However, it all depends on the knife. Fish will change depending on the thickness or how we cut."

Not surprisingly, there is a significant bond between Ishii and his knives. He still has his first knife set, given to him by his father when he got his first job. One of these is more than 20 years old. Sharpening over the years has reduced its length from 45cm to 25cm: "but it's still usable for me."

However, this "special relationship" between chefs and their knives is not just confined to Japan. According to French chef Hélène Darroze, it is quite normal. "I am very linked to mine and I don't want other people to use and to touch my knives – that's something very personal," she explains.

Of course, Patel is no different. His first knife was given to him in 1988 from Masamoto, the chef he worked for in Japan, and he still carries it with him today: "It changed the way I cut, it changed the way I looked at food. It changed everything."

I must admit, Patel's enthusiasm is infectious; the allure of cutting food like a pro has me hurrying home to practice with my only, and disappointingly blunt, chef's knife.

But even if you don't choose to spend 10 years training in the art of cutlery, the message of any professional chef seems clear: buy yourself one good blade and keep it sharp. After all, considering the amount of knives this troupe of experts own, you wouldn't want to disagree.

How to choose the right knife

The blade of the knife should allow you to excel in crushing, chopping, mincing, carving and slicing. The general principle of cutting food is that a long and narrow blade is used for cutting through raw or cooked flesh of meat and fish and a straight, wide blade for cutting vegetables, which will also allow you to sweep up the chopped vegetables easily. So, it's very useful to have a multi-purpose European chef's knife, which will usually have a third of the blade wide and flat at the back and is slightly curved to the point. Blades can be up to 10in long, but smaller blades that are 5-6in do the job and may be more comfortable for those with smaller hands.

A sharp and durable knife is most important – so a blade with a hard, high-carbon core that is laminated with a soft steel will allow you to sharpen it very quickly and easily with a whetstone, frequently and for a long time.

You need to feel at ease when holding your knife, so look for a blade that has sturdy leverage and a secure and full-length tang, which is the metal at the back of a blade connected to the handle, providing more balance and making it more durable. Quality knives also have their handles attached to the clamp with rivets.

Even a very good quality knife needs to be maintained well, so storing knives in wooden blocks or drawers is not a good idea if you want to keep your blade sharp. The best options are to keep knives in sheaths, magnetic blocks or hang them on magnetic strips.

Aisha Gani