Heat 2 TBS vegetable oil in an ovenproof frying pan big enough to fit the 4 lb of sirloin. Season the sirloin all over with 1 tsp of salt and, when the oil is very hot, gently brown all over.

Add 3 TBS of unsalted butter, 1 bulb of garlic and herbs (¼ bunch of thyme and ¼ bunch of rosemary) and allow the butter to foam. Spoon it over the meat to baste, turning often, for 5 minutes. Put the entire frying pan into the oven and turn the sirloin over every 5 minutes, basting with the butter.

Remove after 15 minutes for rare, 22 minutes for medium and 30 minutes for well done. Allow to rest for 10 minutes before carving.