Once fiddly French cordon bleu, Posh food today tends to be thought of as food that is not pre-packaged or made for convenience, but instead is fresh, seasonal, free range and organic.

Salmon was once a food that was thought of as posh, but now, after the mass farming of the fish it is not deemed as decadent as it once was, the same applies to certain cuts of meat. Posh food now is all about being wholesome, on the whole.

But aside from posh food for everyday folk, there are certain foods that evoke a sense of pure decadence and luxury, and only appear on the dinner plates of the rich. Sometimes it is because of their rarity, and sometimes because of the length of time that it takes to prepare, store or mature.

Here are a few of the best and how much it costs the rich connoisseur to sample the delights of the most expensive larder in the world.

Matsutake Mushrooms

The Matsutake, or Mattake mushroom is rare to almost extinction, and so, this is what makes them expensive to excess.

This smoky spicy smelling fungus grows in Japan (as well as Korea, China and some Scandinavian countries) and, in the past, has been successfully harvested during the autumn months.

However, more recently blight has affected the tree where the mushroom naturally flourishes. This kills the tree and so leaves little natural habitat for which the mushroom to flourish in.

Harvesting the Matsutake is relatively easy but it is yet to be farmed successfully, so sourcing it in an increasingly hostile wild environment pushes up the price up to $2000 per kilo.

Iranian Caviar

Iranian caviar also known as Almas caviar is extremely rare, and, as caviar is the most expensive food in the world by weight, it is the food solely of the rich.

The only known outlet to sell this Iranian delicacy is in London, England. The Caviar House & Prunier in Picadilly sells a kilo of Almas caviar packaged in a 24 carat gold tin for £16,000, or about $25,000!

Wagyu Steak

Steak has always been presumed expensive, but factory farming methods have brought the price down dramatically. Not so the steak of the Wagyu cattle.

A Wagyu steak comes from Kobe beef, which is a rare Japanese breed of cattle that are apparently fed a diet that contains beer; and are massaged daily. Although high in fat, a full Wagyu rib eye will set you back a whopping $2800 at Craftsteak in New York.

Italian White Alba Truffle

The second most expensive food by weight, the truffle is a rare delicacy and so known as the King of Fungi.

Truffles are difficult to cultivate, so as they need to be sourced by pigs or dogs, this is timely, so expensive.

The most expensive truffle ever weighs in 1.51 kilograms (3.3 lbs) and cost $160 406 USD, it was sold to a property tycoon from Hong Kong for his wife, who is said to love Italian White Alba Truffles