How to cook (or braai) a fillet of beef to perfection

I must have tried ten different ways to cook a lovely fillet of beef, with results ranging from an incinerated log to a bloody shame. After much experimentation, I reckon this is the way to go. This method gives you a lovely crusty brown skin on the outside, and a melting, rare and tender inside.

The problem with roasting or braaing a fillet is that, by the time you've achieved a satisfactory glistening mahogany colour on the outside, the inside is over-cooked.

So try this:

Three hours before you're going to cook it, take the fillet out of its packaging (strictly speaking, it shouldn't be wrapped in plastic at all, but let's not be precious about this), drain off all bloody liquid, pat it quite dry with a paper towel and put it into a ceramic dish so it can slowly come up to room temperature.

One or two hours before cooking, trim and flavour the fillet. Using a sharp knife, peel or cut off any silvery membrane on the outside of the meat. Slice off the thin tail-end of the fillet (and keep for lunch tomorrow) or double the thin end over and tie it to the main fillet with string. Don't worry if one end is much thicker than the other (the thick end will cater for those who like their fillet very rare, and the thin end will do for those who like brown beef).

Whether you're braaing or frying, preheat the oven to 190°C, and place a metal roasting pan in the oven.

Put a fat dollop of good prepared mustard (such as Dijon mustard) in the palm of your hand and smooth it all over the fillet. Sprinkle liberally with olive oil and a little salt, and grind over plenty of fresh black pepper. Add any other flavourings that you think might be good (a dash of good soy sauce or a very light dusting of mild curry powder are to be recommended, but don't use fresh garlic, which turns bitter when it browns in hot fat).

If you're frying: Heat one tablespoon of olive oil in a frying pan over a high flame. The fat should be very hot, but not actually smoking. Put the fillet into the pan and cook one one side for about two minutes, or until it's a rich brown colour. Turn the fillet and brown it all over; this shouldn't take longer than six or seven minutes. Now add a tablespoon of butter to the pan and turn the fillet over to coat.

If you're braaiing: Make sure your coals are blazing hot. Toss the well-oiled fillet directly onto the grid and brown it all over; again, this should take about six or seven minutes.

Now put the fillet onto the heated roasting pan and bake in the pre-heated oven for 10-25 minutes, depending on the degree of pinkness you want. (A slim fillet takes about 10 minutes; a full-size one 15-25. If you're not sure, cut a deep slit in the thickest part of the fillet - on the underside!) to check for doneness). Remove from the oven, wrap in tin foil (or in cling-film) and set aside to rest for 5 minutes. If you want to serve your fillet really hot, cover the package with a bath towel or blanket.

Unwrap the fillet and carve into thick slices.