Preheat the oven to 180 degrees C. With a sharp knife, trim all the fat from the beef joint. Season with pepper.
Place the fresh herbs in a food processor with the Dijon mustard and process until very fine, scraping down the sides of the bowl occasionally. Transfer to a small bowl. (If using dried herbs, just mix with the mustard.)
Spoon the herb mixture onto the beef and spread it evenly to cover all sides. Put the oil in a large roasting pan and add the beef joint. Roast for 30 minutes.
Arrange the onions, zucchini and cauliflower florets in the pan around the joint. Toss the vegetables to coat them thoroughly with the pan juices.
Roast for a further hour or until a thermometer inserted in the centre of the joint reads 70 degrees C for medium. Turn the vegetables occasionally so that they cook evenly.
Remove from the oven. With a slotted spoon, transfer the vegetables to a serving dish and keep them warm. Place the joint on a carving board, cover and leave to rest for 5 minutes. Slice the beef and serve with the vegetables.
I loved the cauliflower. I added balsamic vinegar to the veggies and had my children wanting more. A very happy mum. Try as I might, I couldn't process the basil finely enough - I think a mortar and pestle might work better? Don't know...but overall, an excellent idea. - 09 Aug 2011