SteakK used to be simple. Back in the day the choice was between rump or fillet. Sirloin came later and was considered "unusual". These days, however, it's about far more than the cut. There are health issues to wrestle with, the bamboozling range, animal feed and most recently how old was the animal your steak came from?Foodies are going wild for old Spanish cows. That's old, as in animals that are eight years plus. Many cattle are slaughtered before they reach two-and-a-half.According to Nemanja Borjanovic, a Serbian-born owner restaurateur in London, its flavour is deeper, stronger and "has length, like wine - the taste stays with you".The meat is imported from one of two districts in Spain, Galicia or the Basque Country."Super ageing" is the other obsession of the steak aficionado: 14 to 30 days is common but some butchers are ageing the meat for as much as 365 days...