Best-of-the-best beef wellington

Method

1. To make the duxelles, whizz the mushrooms, shallot and olives to a coarse paste in a food processor. Melt the butter in a large frying pan over a high heat, then add the paste and thyme leaves. Fry for about 10 minutes until all the liquid from the mushrooms has evaporated. Add the soy sauce and vinegar, then continue cooking and stirring for a few more minutes until the paste dries out. Set aside to cool.
2. To make the pancake, add the spinach, basil, egg, milk and flour to a bowl and use a hand blender to quickly whizz everything to a smooth batter. Cover and chill for 30 minutes. Meanwhile, heat the oven to 200°C/180ºC fan/ gas 6 with the baking tray inside, drizzled evenly with the oil.
3. Once hot, work quickly and pour in roughly half the batter, then tilt the tray to ensure it thinly covers the base. Set aside – the residual heat of the tray should cook the pancake. You may not need the remaining batter (but have it to hand in case your first pancake tears. Or use it for a savoury pancake with cheese).
4. Heavily season the beef with salt and pepper all over. Put a large frying pan over a high heat with the oil and, once smoking hot, add the beef. Quickly sear all over, including the ends, then remove from the pan and leave to rest. Once cooled to room temperature (this won’t take long), spread the mustard all over.
5. Line another large baking tray with baking paper. Unroll one of the sheets of pastry and use a rolling pin to roll it a little thinner and bigger until you’re confident it can completely encase the piece of beef. Carefully transfer it to the tray, then lay the cooled pancake over the top. Spread the pancake with the chicken liver parfait, followed by the duxelles. With one of the longer sides of the pastry facing you, lay the beef across it about 9-10cm from the right- hand end. Take the right-hand end of the pastry and roll it up and over the beef, then roll the beef in the pastry until it’s completely covered and the seam is on the bottom. Tuck the sides in and seal, then tuck any excess pastry underneath. Brush liberally with beaten egg.
6. Take the extra half sheet of pastry and lay it flat on some baking paper. Use a lattice roller to cut out a lattice shape or, if you don’t have a lattice roller, you can create the same effect using a ruler and a knife. Ensure the pastry is chilled and work quickly. With a short side facing you, put a ruler on the pastry vertically, 1cm in from the left. Using a small knife, make 2cm cuts at 2cm intervals along the side of the ruler, then move the ruler 1cm along to the right and make another line of 2cm cuts but shifted up/down 2cm (so the cuts aren’t next to each other). Repeat these 2 lines of cuts all the way along the pastry.
7. Carefully pick up the latticed sheet, then gently stretch it out to create a net like effect. Drape it over the wellington, trimming and tucking underneath where needed. Brush again with the egg wash, then refrigerate for 30 minutes (but no longer) to chill the pastry while the meat remains at room temperature.
8. Meanwhile, heat the oven to 200°C/180ºC fan/gas 6. Bake the wellington for 35-40 minutes for a medium-rare finish. Push the thermometer probe through the pastry into the centre of the meat: it should read 50°C and 52-54°C after resting. Rest for 12 minutes before carving using a large serrated knife.