Alongside the beans are spongy heads of broccoli, waxy red peppers, fat garlic bulbs and spring onions the size of truncheons. They"re all part of an incredible bounty of produce that is grown in La Huerta each year, despite the fact that its fields enclose Spain"s third-largest city. The secret is an ingenious maze of channels, ditches, weirs and floodgates invented by the region"s Moorish rulers 1,200 years ago.