It's what they're calling "extreme aged beef". M Restaurants are challenging just how long you really should age beef for by putting 175-day aged USDA Prime Rib Eye on the menu. And they say that the effect of this long-term aging is that "the resulting flavour is unique - punchy, beefy and almost cheesy in taste."
So if you fancy some of that cheesy beef, it's on the menu from September at £17.50 for 100g (with a minimum size of 500g).
M Restaurants are at Threadneedle Street and Victoria Street. For more, follow them on Twitter @mrestaurants_.