Cook the pasta in a large saucepan of boiling water according to the packet instructions. Add the broccoli florets during the last 2 minutes of cooking, then drain.
Meanwhile, preheat the grill to medium. Grill the steak 10cm from the heat for 4 minutes on each side for medium or until cooked to your liking. Transfer the steak to a cutting board and thinly slice across the grain on the diagonal.
To make the dressing, combine the yogurt, mayonnaise, vinegar and basil in a small food processor and process until smooth. Transfer the dressing to a large serving bowl.
Add the steak and any juices accumulated on the cutting board to the bowl with the dressing, then toss to coat. Add the pasta, broccoli, tomatoes and onion to the bowl and toss again.
Some more ideas…
*Sirloin is a relatively lean cut of meat. Lean cuts should not be grilled past the ‘medium’ stage, or they'll toughen. Very thinly slicing the meat across the grain also helps to enhance its tenderness. *Corkscrew-shaped pasta such as rotelle or fusilli is just one option for this dish; you could use any other short pasta shape. *The salad can be made ahead of time and refrigerated. Bring the salad back to room temperature before serving.
Enriched pastas and other grain foods are great sources of folate, a B vitamin that is essential for a healthy heart.