There aren't many naturally blue foods out there, so here's one to get excited about. This Dutch heirloom pea can be picked young and eaten raw as a colourful snap pod, or left to swell on the vines and harvested as a plump pea for cooking. It's not easy being a blue pea – give them support for up to 2m. To use the pod and peas, pick them very young. This versatile variety has lovely purple flowers with a faint scent, which also happen to be edible. Traditionally, they are soaked overnight and then pan fried with onions and bacon – even when cooked, the pods will stay a cool purple colour. Now that's a winter dish worth growing a plant for.