In a small saucepan, cook carrots in a small amount of boiling water for 4 minutes. Add the beans; cook 4-5 minutes longer or until vegetables are crisp-tender. Drain; chill in ice water. Drain and pat dry; place in a large bowl. Add radishes and onion.
In a small bowl, whisk the lemon juice, oil, sugar, mustard, garlic, salt and cumin. Pour over bean mixture; toss to coat. Cover and refrigerate until serving. Sprinkle with sesame seeds. Yield: 4 servings.