Bring a large pot of salted water to a boil and add the green beans.

Blanch the green beans for 3 to 4 minutes, until bright green and just tender with a slight snap left.

Drain the green beans and plunge them into a bowl of ice water for 2 minutes to stop the cooking and lock in the color.

Drain the green beans again and pat dry.

Whisk the olive oil, red wine vinegar, sugar and salt in a large bowl until the sugar dissolves.

Add the green beans, kidney beans, chickpeas, red bell pepper and red onion to the bowl.

Toss everything together until well coated in the dressing.

Cover and refrigerate for at least 4 hours, or up to 2 days, stirring once halfway; the beans should taste tangy all the way through once ready.