Cook beans in boiling water to cover 3 to 5 minutes or until crisp-tender; drain. Plunge into ice water to stop the cooking process; drain and set aside.
Heat oil and next 5 ingredients in a saucepan over medium heat.
Combine beans, onion, and garlic; drizzle with warm vinaigrette, tossing to coat. Cover and chill at least 3 hours. Discard garlic clove.