1.Preheat oven to 240C. Brush beef with oil, place thyme sprigs on top and secure with kitchen string. Season to taste with salt and pepper and roast for 15 minutes, then reduce oven to 180C and roast, turning and basting occasionally, until medium-rare (1-1¼ hours). Transfer to a plate (reserve pan juices in pan) and set aside in a warm place to rest, covered with a double layer of foil (20-30 minutes).
2.Meanwhile, for roast potatoes, bring a saucepan of salted water to the boil, add potatoes and cook until par-boiled (10 minutes). Drain, shake in pan to crush edges slightly, and set aside. Increase oven to 250C. Heat lard in a separate roasting pan over high heat until hot, add potatoes and garlic (be careful, hot lard will spit), toss to coat, season to taste and roast, turning occasionally and adding sage to pan 5 minutes before potatoes are golden and cooked (30 minutes). Before serving, scatter with sea salt.
3.Add flour to beef roasting pan and stir over medium heat until mixture is bubbling (2-3 minutes), then add thyme leaves and wine and cook, stirring continuously, until wine is absorbed. Gradually add stock, stirring until mixture is smooth, then season to taste, bring to the boil and stir occasionally until the gravy has a thin sauce consistency that coats the spoon (5 minutes). Keep warm.
4.Carve beef and serve drizzled with pan gravy and with roast potatoes.
For brown chicken stock, roast chicken carcasses at high heat until brown, then cover completely with water, bring to the boil, skim scum and cook over low heat until stock is well flavoured (3-4 hours). Shop-bought lard is fine, but making your own yields the best flavour: cook chopped pork back-fat in a saucepan over low heat with 5mm water in the base (to prevent burning) until the fat renders, then strain and refrigerate until fat solidifies. It can be stored in the refrigerator for up to a month. Allow plenty of time to rest meat so the proteins relax and the juices settle. It really makes the difference for a juicy, tender result. Cover the meat loosely with foil (unless it has crackling, which would lose its crunch) and rest it in a warm place. Large cuts of beef, veal and pork need around 30 minutes, chicken 15 minutes and fish 5-10 minutes.
Drink Suggestion: Ballsy Barossa shiraz. Drink suggestion by Max Allen.