for the filling:
- 300g lambs’ kidneys (about 6) (replace with the same weight of button mushrooms if you cannot find)
- 500g chuck steak, chopped into 2cm pieces
- 1/2 teaspoon salt
- 1/2 teaspoon freshly ground black pepper
- 1 teaspoon mustard powder
- 2-3 tablespoons cooking oil (I used beef dripping)
- 1 onion, peeled and finely diced
- 1 carrot, peeled and finely diced
- 2 tablespoons red wine vinegar
- 1 teaspoon anchovy sauce
- 1 tablespoon (20g) tomato puree
- 1 teaspoon fresh thyme, leaves only (or 1/2 teaspoon dried thyme)
- 1 1/2 – 2 cups (480ml – 600ml) homemade stock (I used beef stock, but chicken stock works well too)
for the pie crust:
- 1 celeriac head (800g net)
- 3 tablespoons olive oil
- 1/2 teaspoon salt
- 1/4 teaspoon freshly ground black pepper
- 1 egg, lightly beaten with a fork
Prepare the kidneys (or mushrooms):
- if using kidneys: remove the thin white membrane that encases the kidney – it should peel off easily. Slice in half lengthways. Snip out the fatty white core using a small pair of sharp scissors (the core is attached by a series of thin white tubes that radiate outwards in a starburst pattern, so simply snip off each tube in turn). This is a bit fiddly so will take a few minutes. Chop the kidneys into 1cm pieces and place in a small bowl.
- if using mushrooms: rinse the mushrooms under a cold tap, gently wiping off any soil. Halve or quarter, depending on the size. Transfer to a small saucepan. Add a tablespoon of cold water and cover with a lid. Heat over a medium heat until the mushrooms release their juices and are boiling in the liquid. Remove the lid, and increase the heat to high. Continue to boil until all the liquid has evaporated and the mushrooms start to sizzle. Transfer to a small bowl.
- Season the meat. Place the diced steak in a large bowl. Combine the salt, pepper and mustard powder. Sprinkle the seasoning over the meat and gently toss until evenly coated, using your hands.
- Brown the meat. Heat 2 tablespoons of cooking oil in a heavy-based casserole over a medium-high heat. When a few drops of water sizzle and evaporate upon contact with the pan, add the meat. Sear the steak in 2-3 batches until browned all over with a caramelised crust – about 3-4 minutes a batch. Add more cooking oil when necessary. Do not overcrowd the pan. Transfer the browned meat back to the large bowl. Repeat with the kidney (or mushrooms), then transfer to the same bowl as the steak.
- Saute the vegetables. Add the carrot and onion to the casserole, and cook until it starts to brown – about 8 minutes. Add the red wine vinegar and leave to cook until completely evaporated. Stir in the anchovy sauce, tomato puree and thyme.
- Deglaze the pan. Add a little of the stock, and scrape off all the tasty browned bits from the bottom of the pan with a spatula.
- Simmer the stew. Return the meat to the casserole, and add 2 cups / 480ml of the stock. Set aside the other 1/2 cup / 120ml – you will only need this towards the end, if the sauce starts to dry out. The meat should be more-or-less submerged in liquid. Top up with a bit of extra stock / water if this is not the case. Bring to the boil, then reduce the heat to low. Leave to simmer gently, uncovered, for 1 hour 30 minutes, stirring occasionally.
- The liquid should reduce considerably, until the meat sits in several generous spoonfuls of gravy. If the sauce starts to dry out toward the end, top up with a bit more of the stock. If you have too much liquid at the end, remove the meat with a slotted spoon and boil the liquid over a high heat until reduced.
- Cook the crust. Meanwhile, prepare the crust. Preheat the oven to 180°C/355°F.
- Trim the root tendrils from the celeriac and slice off the thick skin – expect to lose about a quarter of the net weight. Chop in half and grate (I used the grater attachment on my food processor). Place in a large bowl and add the olive oil, salt and pepper. Toss until evenly coated using your hands.
- Thinly scatter half of the celeriac over two large roasting trays in a single layer. Transfer to the oven and cook until just starting to colour – about 10 minutes. Stir the celeriac and turn the tray halfway through for even colouring. Remove from the oven and place in a large bowl. Repeat with the rest of the celeriac. Set aside until needed.
- Assemble the pie. Spoon the filling into a 23cm/9″ pie dish. Tip the beaten egg into the celeriac, and mix until fully blended. Use your hands to scatter the celeriac over the top of the filling.
- Transfer to the oven and cook until starting to brown on top – about 15 minutes. Remove from the oven and leave to stand for 5-10 minutes. Transfer the pie dish to the table and serve hot.