Bring a large saucepan of water to the boil. Fill a bowl with iced water. Add the broccoli to the pan and simmer for 1–2 minutes or until tender but still crisp. Using a slotted spoon, transfer the florets to the iced water.
Return the pan to the boil and add the peas. Simmer for about 2 minutes, then transfer to the iced water.
Return the pan to the boil again and add the carrots. Simmer for 3–4 minutes or until tender but still crisp. Add to the iced water.
Bring the pan back to the boil. Add the pasta and cook according to the packet instructions. Drain in a colander and rinse under cold running water.
To make the dressing, put the yogurt, mayonnaise, mustard, wine vinegar and pepper in a bowl and stir until thoroughly blended.
Drain the vegetables and toss with the pasta and dressing. Add the celery and onion. Sprinkle over the herbs and mix well. Serve at room temperature or chilled.