Help !! I'm roasting a beef for the first time !!!

[Summerfruit]

Its 500 g, I rubbed butter on it, pepper, salt, rosemary...How long should I cook it for ? I like it medium rare !! Thank you !!!

It will cook fast as it's slow. Normally you'd say 25 minutes per half plus another 25 for "the pot". I'd say put it on hot for about 15 minutes, then turn down and cook it for another 15 and then test it. But I wouldn't have thought it would take more than 40.

Thank you blingloving ! Will do that !!!

A beef? Bloody hell how big is your oven ?