Broccoli, Chickpea, and Cherry Tomato Salad

In a large saucepan with a steamer insert, bring 1 inch of water to a boil. Add broccoli, cover, and steam until crisp-tender, 4 to 6 minutes.

In a large bowl, whisk together mustard, red-wine vinegar, olive oil, and onion; season with coarse salt and ground pepper. Add tomatoes, chickpeas, and broccoli. Toss to coat with dressing. Let cool 5 minutes. Serve at room temperature or chilled.