1) Preheat the oven to 200C/Gas 6.
2) Place the edamame, corn, spring onion, garlic, olive oil, salt and pepper into a 23 by 33-cm baking tray and stir to combine. Place on the middle rack of the oven and roast for 10 to 15 minutes, until the edamame just begins to brown. Remove from the oven and place in the refrigerator until completely cool, approximately 30 minutes.
3) Add the tomato, basil and vinegar to the edamame mixture and toss to combine. Taste and adjust seasoning, as desired.
Serve chilled or at room temperature.