Place a pressure cooker over medium heat and add enough oil to coat the bottom. Sweat the celery, leeks and carrots, approximately 10 min. Once soft, remove from the pan and set aside.
Return the pan to the heat and add a bit more oil, cook the mushrooms for approximately 10 minutes until caramelized. Set aside.
Place the pan back on the heat, add more oil and cook the onions and star anise. Cook for 10-15 minutes or until soft and caramelised. Add all of the cooked vegetables back in the pan and cook for an additional 5 minutes, remove from the pan.
Add a splash of water to deglaze the bottom of the pan. Add the liquid to the cooked vegetables.
To braise the oxtail, place a deep pan over a medium-high heat. Once smoking hot, add enough oil to coat the bottom of the pan and brown the oxtail, in batches if necessary.
Once the oxtail pieces are well browned, tip any excess fat out of the pan, return to the heat and deglaze by adding the red wine and brandy. Flame off the alcohol by setting fire to the fumes carefully with a match.
Once the flames have died, add the tomatoes, thyme, bay leaf, cooked vegetables as well as the browned oxtail, peppercorns and both chicken and beef stocks. Bring the pressure cooker to full pressure, reduce the heat and cook for 2 hours.
To make the pastry, mix the flour, suet, salt and baking powder together in a bowl. Sprinkle 300ml ice cold water over the mixture and, with clean hands, work into a smooth dough. Knead lightly and place in the fridge to rest for 10-15 minutes.
Divide the pastry into 6 x 100g portions and roll out circles that are approximately 3mm in thickness. Grease the pudding basins with a little butter and line with the pastry circles.
After 2 hours, place the pressure cooker in a sink of iced water to cool completely before removing the lid. Once cool, remove the oxtails from the liquid and pick the meat from the bones. Strain and discard the vegetables and return the liquid to the pan. Place over a high heat to reduce by two-thirds or until a thick glaze is formed, removing any scum that comes to the surface with a ladle.
Remove the pan from the heat and save some sauce aside to pour over the pudding or inject just before serving. Add the picked meat, kidney pieces and some of the sauce and season with salt and freshly ground black pepper. Stir together before spooning into each pudding basin until they are full of meat.
With the remaining pastry, roll out lids to cover the basins (approximately 6mm in thickness). Brush the edges with egg wash and press down firmly to seal, trim off the excess dough.
Place a small square of parchment paper on top of each pudding and secure with an elastic band. Place the puddings in a wide saucepan with enough water to come ¾ of the way up the sides of the basins. Allow the water to come to a simmer and cook for 35 minutes. Carefully remove the puddings from the moulds.
Take some of the warm sauce and using a syringe inject into the pudding. Serve immediately.
