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 simmer for 2 minutes (tender) to 3 minutes (tender).

Drain in colander then run under cold tap water to cool (or plunge into bowl of ice water).

Drain well then pat dry with clean dish towels.

Place beans in a bowl with tomato and onion. Drizzle with dressing, then toss. Garnish with feta. Serve!