Vacío

Vacío is one of the finest cuts of the Argentine asado, and also one of the most commonly ruined by rushing it. There's only one rule: gentle heat and time. Done properly it comes out golden and crisp outside, juicy and tender inside.

The fire: how to gauge it with your hand

Hold your palm at the height where the meat will sit. If you can stand it for 7 or 8 seconds before pulling away, that's gentle heat: exactly what vacío wants. If you can only manage 3 or 4 seconds, it's too hot — wait, or spread the embers out. Few steady embers beat a big blast of heat.

Does it need marinating or prepping first?

No. Fresh vacío needs no marinade: the membrane covering it holds the juices in during cooking, so don't remove it. Just take it out of the fridge 30–45 minutes ahead so it loses the chill, and salt it with coarse salt as it goes on the grill.

Cooking it, step by step

• Start with the membrane side facing the embers. That's where it spends most of its time: 60 to 80 minutes over gentle heat for a whole piece.
• Turn it once only, when you see the juices starting to surface on top and the membrane is golden and crisp.
• Give it another 20 to 30 minutes on the second side, until it feels firm but still gives a little in the centre.
• Let it rest for 5 minutes before slicing, always against the grain.

Common mistakes

High heat to "speed things up" (burnt outside, raw inside), turning it over and over, and piercing it with a fork — use tongs and the juices stay in. If there's any left, cold in a sandwich the next day is a classic.

You don't always have a grill, and vacío in the oven works far better than people expect. The logic is the same: low temperature and time. The difference is there's no fire to watch.

Before it goes in

Take it out of the fridge 30 minutes ahead and salt it with coarse salt on both sides. Don't remove the membrane: in the oven it does the same job as on the grill, holding the juices in.

Cooking it

• Oven at 160 °C, with the piece in a roasting tin, membrane facing up.
• Cover with foil and leave it for 2 hours. No peeking every ten minutes: each time you open the door you lose 20 °C.
• Uncover and turn it up to 200 °C for the last 20 minutes, so the membrane browns and crisps.
• Rest for 10 minutes before slicing, against the grain.

Use the juices

There's a concentrated juice left in the bottom of the tin that is pure flavour. Pour it into a small pan, reduce it for two minutes over high heat and spoon it over the slices. It's the thing that gets the result closest to an asado.