Preheat the oven to 180°C / 160°C fan-forced. You will need a shallow casserole for the lamb, and a roasting tray for the vegetables.
Open out the boned lamb leg and place it skin-side down. Trim off any excess sinew or fat and then season well.
For the stuffing mix all the ingredients together in a bowl. Make sure you season well and use a little more olive oil if the crumbs seem too dry. Spread the stuffing mixture over the lamb, roll it up and tie it with butcher's string in about 5 places to keep the roast in a nice shape.
Prepare the roast vegetables - combine the vegetables and herbs in a bowl, coat liberally with olive oil and season well with salt and pepper. Tip onto a roasting tray in an even layer, giving each vegetable its own space.
Heat the casserole over medium heat with one tablespoon of olive oil and lightly brown the lamb all over. Put it aside.
Mix the beetroot wedges in a bowl with the vinegar, herbs, orange peel and juice, one and a half tablespoons of olive oil and season with salt and pepper.
Heat the casserole, adding another tablespoon of oil over medium heat. Add the garlic cloves and cook for about a minute before adding the beetroot mixture, the red wine and water. If you have a lid for the casserole put it on now and cook over medium heat for 10 minutes. Remove from the heat, remove the lid and place the lamb on top of the beetroot mixture.
Place the lamb and the tray of roast vegetables in the oven and bake for about 40-45 minutes for pink lamb or until the centre reaches 55°C as measured with a meat thermometer. Remove the lamb from the casserole to a plate, cover with foil, then put them aside and keep warm.
The beetroot and tray of roast vegetables will most probably need more time in the oven. Increase the oven heat to 200°C / 180°C fan-forced and continue to cook the beetroot until it is tender, and the vegetables until they are golden and tender.
For the mint sauce, mix all the ingredients together in a bowl. Pour a serving jug. Set aside until required.
Separately, bring a saucepan of salted water to a boil and cook the stalks and leaves of the beetroot for 10 minutes. The stalks will take longer so add these first. Dress lightly with some olive oil, salt and pepper.
Once everything is ready, remove the string from the lamb and slice. Serve with the beetroot and any juices in the casserole along with the beetroot leaves and stalks and the jug of mint sauce.