BBQ beef Wellington with a Marmite mushroom crust

The cook

1. 01

   Step 1DRY THOSE MUSHROOMS

   Melt the butter in a wide frying pan over a medium heat. Soften the shallots for 4–5 minutes, then add the garlic, thyme and mushrooms. Cook over a medium-high heat for 20–25 minutes, stirring frequently, until the moisture has evaporated and the mixture is a dark, spreadable paste. Stir in the Marmite for the final minute. A spatula dragged across the pan should leave a dry track. Wet mushrooms mean soggy pastry. Spread thinly on a clean tray, let the steam escape, then refrigerate until completely cold.

2. 02

   Step 2SEAR OVER LUMPWOOD

   Light lumpwood charcoal and arrange a hot direct zone with a cooler area alongside. Pat the fillet thoroughly dry, rub with the oil and season lightly with salt and pepper. Sear over the hot coals for 6–8 minutes in total, turning with tongs to brown every surface, including both ends. Chase colour, not a cooked centre. Move away from any flare-ups.

3. 03

   Step 3COOL COMPLETELY

   Brush the seared fillet with Dijon and place on a clean rack over a tray. Let the fierce heat escape for 15 minutes, then refrigerate until completely cold, allowing roughly 45–60 minutes or longer if needed. Don't wrap warm beef: it melts the pastry butter and creates steam where you don't want it. The prep time includes chilling, but temperature wins over the clock.

4. 04

   Step 4BUILD THE MUSHROOM JACKET

   Lay two overlapping sheets of cling film on the worktop. Arrange the prosciutto in an overlapping rectangle wide enough to enclose the fillet. Spread the cold mushroom mixture evenly over it, leaving a small border. Put the cold beef along the near edge and use the film to roll everything tightly around it. Twist the film ends to firm up the shape, then refrigerate for 20 minutes.

5. 05

   Step 5WRAP THE PASTRY

   On a lightly floured surface, roll the pastry to roughly 3–4 mm thick, large enough to enclose the beef with a small overlap. Remove every bit of cling film, place the beef on the pastry and brush the joining edges with beaten egg. Wrap snugly, trim away excess and seal the ends without building up thick pastry plugs. Set seam-side down on baking parchment on a metal tray. Brush with egg, lightly score a pattern without cutting through and make two small steam vents on top. Chill for 20 minutes.

6. 06

   Step 6SORT THE INDIRECT HEAT

   Set the covered barbecue to a steady 220°C at cooking-grate level. On a kamado, fit the heat deflector and use a raised rack. On a kettle, bank the coals on either side with a clear centre and position a raised rack over that centre. The Wellington tray must sit above the indirect area, with an air gap beneath and no direct flame below. Add no smoking wood. Let the temperature settle before baking.

7. 07

   Step 7BAKE UNTIL GOLDEN

   Put the chilled Wellington, still on its tray, onto the raised rack and close the lid. Bake for roughly 40–50 minutes, checking the centre temperature from 30 minutes with a probe inserted through one end into the middle of the beef. Rotate the tray once if one side colours faster. Aim to remove it at 52–53°C for a final temperature around 55°C after resting. The pastry should be deep golden and cooked underneath; loosely shield the top with foil if it colours too quickly. Fillet thickness matters more than the timer.

8. 08

   Step 8REST, THEN REVEAL

   Rest uncovered on the tray for 20 minutes, checking for a final centre temperature around 55°C. Don't swaddle it in foil — trapped steam softens that pastry. Lift onto a board and cut thick slices with a sharp serrated knife, using gentle strokes rather than squashing down. Pink beef, dark mushrooms, crisp pastry. There's your Christmas centrepiece.

9. 09

   Step 9LOOK AFTER THE LEFTOVERS

   Refrigerate leftovers within 2 hours of cooking and use within 48 hours. For tomorrow's sandwich, lift the cold beef from its pastry jacket, slice thinly and pile into bread with mustard and crunchy leaves. The pink-centred cooking target here is for whole, intact beef; anyone advised to avoid undercooked meat should have a thoroughly cooked portion.