MELBOURNE may be the most liveable city in Australia, but we all know those south of the border certainly pay for it.

We know it’s the most expensive city in the world to buy beers and cigarettes, but it’s also now the most expensive place to buy a hot dog.

Yes, a hot dog. A sausage wrapped in bread with a squirt of a condiment.

A new hot dog has popped up in Melbourne, and boy it’s going to cost you.

All those who wear Tiffany and drive a Rolls Royce, gather your riches because you may be the only ones who can afford to splurge on this gourmet grub.

Maille Mustard’s Haute Dog, is being sold for $100.

It doesn’t have cheese, onion, not even tomato sauce, but it’s said the be the most exclusive dog in the world — it would want to be for that price.

For $100 you may expect to sit down at a fancy restaurant with neatly folded napkins and table water, but you’ll be getting your hot dog straight from a food truck at Melbourne’s Good Food and Wine Festival.

The $100 hot dog is a grass-fed sausage in a bun, with just a strip of mustard.

It seems pretty plain, so what makes it so special? Apparently it’s all in the mustard.

Squirted onto the beef snag is a French-made Chablis white wine and black Perigord truffle mustard.

“It’s the most exclusive mustard in the world,” Maille national brand manager Mark Gluck said.

It’s a taste that will tickle the nostrils, with vinegar and horseradish giving the condiment that hot mustard feeling.

The black truffles in the mustard come from France and can only be picked five months of the year between October and March.

While good hot dogs are usually judged on how much you can fit in the bun — bacon, onion, cheese, pickles — we might be underestimating the power of condiments.

“A teaspoon of Dijon mustard added to any dish — whether it’s a salad, pasta dish, pizza base — it will bring out all the flavours in the dish,” Mr Gluck said.

The hotdog is usually a humble snack you chow down on while you’re at the footy on a Saturday morning, but it seems there’s potential for it to be a gourmet eat.