Aging meat is about controlled decay. As the fat breaks down, so does the meat and you lose moisture from it over time. As the cells break down, you get tenderization—it's on a curve of tough versus time. Butchers will say there's no point to aging something for over four weeks because it's not going to make a difference on how tender it is, but I believe that as meat continues to lose moisture, the flavor intensifies.
As long as the conditions are right, aging is absolutely safe. I've been in places where I've tasted aged meat before and it's been a bit green. Slimy meat is not good; it has to be done right. This is the reason we've invested so heavily in walk-in fridges at Lyle's, because for proper aging, you need consistent temperature, air circulation, and humidity. Most restaurants in London are tight on space and might use the walk-in for all sorts of things, but what I wanted here was a fridge that stays closed and is purely for the long-term storage of meat. It allows me to do things that others aren't able to, like hanging whole carcasses and finishing the aging process off myself.
It's a real luxury to be able to take control like this. People know that aging meat and rare breeds have an effect on the quality of the end product, so doing this allows my staff to see first-hand how to get the very best from the meat. They get to see what it's like when it comes in, watch it change in color and texture, and then see how it cooks at the very end. It's a better learning experience for everyone and gives us a chance to play around—cooking from photos without understanding the process is a massive plague in modern cooking.
There is no 'right' way of aging meat—it's a personal thing.
Although the conditions must be constant and building up a relationship with a butcher who understands how important this is imperative, there is no 'right' way of aging meat—it's a personal thing. For example, you can't say that the optimum time for aging pork is six weeks, because it depends on your taste. All across Europe there are myriad ways of doing it. I like dry-aging meat, but some products, like bavette steak, can be wet-aged and it works really well. Wet-aging is a process where you vacuum pack the meat and it breaks down in an oxygen-free environment—you get a really different flavor from it and the French love this method because they like juicy, less-aged beef. In some countries, you get regional variations: The Spanish tend to wet-age beef as a rule, but, if you go to Galicia or the Basque country, they'll dry-age it because it suits their style of cooking on grills.
Right now in the restaurant, I've got a Dexter that's eight weeks old, two Highland ribs that are ten weeks old, and five mutton. We're also aging chicken guts-in. It's an idea borrowed from the French and what's really interesting is not just the increase in flavor, but also texture. The first time I ever cooked aged chickens, it was a revelation—the roasted juices tasted like foie gras. After cooking it, I sent a little bowl of chicken fat to the table with spoons and asked the diners to taste it. Everyone thought it was foie gras fat, but it was just a 12-day aged chicken. White meat doesn't age in the same way red meat does—you can't keep it going for as long—but up to twelve days it works nicely.
We're aging fish at Lyle's, too. The idea came through reading Harold McGee's On Food and Cooking, and it's also a thing old British boys used to go in for at old fish restaurants like Sweetings, which is Fergus Henderson's favorite restaurant. A lot of flat and bottom-feeding fish age fantastically well, so turbot, plaice, and the soles. You get the same breakdown of cells and amino acids and end up with stronger, more complex flavor compounds.
There's a common misconception with fish that it should be eaten straight from the sea. I'm aging Dover sole for up to seven days and we buy with that in mind, working five days ahead. The number of times you hear people saying, "the fish was as fresh as sushi" is crazy, because really, the tuna loin they've eaten is probably about three weeks old. With Dover sole, if you cook it fresh, it's tough and springy. If you speak to the fishermen they'll tell you that you have to age it—it's not the sort of fish you want to cook fresh.
We don't just wing these things, though; the fish has to be carefully cleaned. You have to get rid of the roe and the guts because they don't last. We leave the fish flat and dry in a fridge set at one or two degrees. Some of my chefs were dubious about this at first, but, after aging it for five days, I put a sole in the oven and got them to taste it. They all asked what I had seasoned it with, because it tasted more savory and intense, but of course I hadn't seasoned it with anything—it was completely naked when it went in the oven.
We're not trying to do things that are different just for the sake of it. I feel that if you're doing simple food, you have to put so much extra work in to make sure that these plates stand out. It might require extra effort and extra kitchen space, but I want us to be the people that make that extra effort.
As told to Rosie Birkett