This is a healthy salad that's perfect when paired with a simple sandwich for a light lunch.
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.
Broccoli heads should have tightly clustered florets that are deep green, with no yellow spots. The stalks should be firm with unwilted leaves.