1) Place the mangetout in a bowl and cover with boiling hot water. After 2 minutes, strain and shock the peas in an ice bath. When cool, strain. Cut the snow peas on the diagonal into 1.25cm diamond shapes, discarding the tops and tails.
2) In a medium size bowl, combine the mangetout, spring onions and radishes.
3) In a separate bowl, whisk together the vinegar and oil. Pour over the vegetable mixture and serve.