With probably the world’s fastest-moving food scene, London is never short of a new culinary trend for you to chew on. Whether it’s a poké bowl or a bottomless brunch, seemingly every day a PR manager or restaurateur comes up with a new way to sell their wares. Which is great, of course. There’s nothing like constant low-level FOMO anxiety to maintain your appetite in a big city. But sometimes it’s nice to relax a little, get back to basics, and eat something as old as time.

Enter the sandwich. If you’re going to indulge in the simple novelty of some bread and filling, we’re particularly fond of the Reuben made at Monty’s Deli in Hoxton, which started life as a market stall in 2012, paying homage to the Jewish food of owner Mr Mark Ogus’s childhood. “I was either working from my flat in London or smoking the pastrami in my parents’ back garden,” he says. Thankfully, now settled into his first site on Hoxton Street, things have moved on. “We’re bringing Jewish soul food to the masses of east London, inspired by the Jewish delis of America such as Katz’s in New York and Langer’s in LA,” says Mr Ogus.

Because we’re such fans, we asked for the secret recipe to Monty’s Reuben sandwich. Below, Mr Ogus reveals (almost) all.

The bread

“You need bread that can stand up to being filled properly without giving way. Use real rye bread, with caraway seeds. We use a light rye, but one that still has a good amount of rye flour. Some delis double-bake their bread for an extra-crunchy crust.”

The meat

“Pastrami or salt beef brisket? Or both? Your butcher (or indeed favourite local deli) can provide you with salt beef if you don’t want to make your own. You need a good amount – use 150g as a starting point. It should look a little ridiculous. See below for the exact method.”

The mustard

“We make our own from the seeds. It’s somewhere between spicy English and sweet American, with a good amount of vinegar to cut through the fat. A good deli-style mustard can be found in supermarkets.”

Russian dressing

“This is the mayonnaise-based sauce that makes the Reuben. Each deli guards its recipe closely. Mix mayonnaise, ketchup, a little of this, a pinch of that, and start guarding your own.”

The sauerkraut

“Fermented cabbage should be sharp and salty. Making sauerkraut is as easy as rubbing salt into shredded cabbage and leaving it in a warm place for a while. But if you’re looking to buy some, Vadasz Deli does a good one. Ours is flavoured with garlic and dill.”

The cheese

“We use Emmental, which melts well and has a mild nuttiness, which is what you want. Stronger cheeses just aren’t right, so resist the urge to get creative.”

To toast or not to toast

“Traditionally you’d melt the cheese under a grill. We toast ours in a sandwich toaster, just enough to melt the cheese. My preference is the grill method but our customers love our toasted Reubens. You can recreate the effect at home with a sheet of greaseproof paper in a dry pan over a medium heat. Flip the Reuben after a couple of minutes to melt the cheese.”

For the beef:

• 2-3kg brisket
• 100g pre-mixed cure (you can get salts from smokedust.co.uk)
• 40g sugar
• 20g ground pickling spice

To build the sandwich:

• 150-250g salt beef/pastrami
• 2 slices rye bread
• 1 tbsp Russian dressing
• 1 tbsp (or a healthy squeeze) mustard
• 20g sauerkraut
• 1 slice cheese (such as Emmental)

Mix the ingredients together to make your cure mix, and rub all over the brisket. Wrap tightly in cling film and leave on a plate in the fridge for a week, turning every day.

The night before you want to cook it, soak the salt beef in enough cold water to cover. This will remove excess salt.

Replace the soaking water with fresh water to cover the meat, then bring to the boil. Turn down the heat to a simmer and cook until tender. It should take 3-4 hours.

Spread one slice of bread with the Russian dressing and the other slice with a healthy squeeze of mustard, then place the sauerkraut on the base slice.

Load up the meat, lay the cheese on top and finish with the remaining slice of bread.