Peel and grate 2 of the garlic cloves and the ginger, then mix with the soy sauce, lemon grass, lime zest and juice, sugar and chilli to make a marinade. Pour over the beef and marinate for at least 3 hours, or ideally overnight, turning occasionally. Strain the marinade and reserve.
Preheat the oven to gas 7, 220°C, fan 200°C. Put the quartered carrots, parsnips, cubed celeriac and halved shallots, along with the 4 remaining unpeeled garlic cloves, in a large roasting tin. Drizzle with the sesame
and the olive oil, season and put the tin in the oven.
Put the beef in a separate roasting tray, pour over a little of the marinade and place in the oven. After
15 minutes, take the beef out of the oven and drizzle with the rest of the reserved marinade. Turn the oven temperature down to gas 6, 200°C, fan 180°C and return the beef to the oven. At the same time, turn over the vegetables a few times and baste.
Roast the beef for 10 minutes per 500g for rare meat and 15 minutes per 500g (1lb) for medium meat, covering it with foil if it starts to brown too quickly on the top. Once cooked to your liking, remove the meat from the oven, cover loosely with foil and leave to rest. To finish cooking the vegetables, sprinkle them with sesame seeds and roast for another 10-15 minutes or until the seeds are golden.
When you’re ready to serve, remove the string from the beef and press the chopped coriander and basil over the top, then slice thinly and serve with the roasted sesame root vegetables and a drizzle of the roasting juices.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.