Combine the Dressing ingredients in a jar and shake well. Set aside - or refrigerate up to 2 days. Bring to room temperature before using.

Bring a large pot of salted water to boil. Add the beans, bring it back up to a boil and boil beans for 60 seconds - no more!

Drain and plunge in ice cold water (or run under cold tap water) to stop them from cooking.

If making ahead, leave in the colander to dry before transferring to the fridge.

To serve, pile the beans on a plate, top with tomato and red onion, drizzled over dressing. Sprinkle with parsley if using.