Clean and dice the mushrooms, onion, celery and carrot.
Remove any loose skin from the head of garlic and crush each clove under the side of a knife.
Dice the chorizo.
In a large skillet or wok over a medium high heat, add a couple of tablespoons of cooking oil.
Brown the lamb shanks on all sides. You may have to do in batches. Add browned shanks to a dutch oven or large casserole dish with a lid.
Discard the oil, as fat would have rendered from the lamb. Keep any brown bits from browning the lamb.
Add a couple more Tbps oil and the chorizo. Sauté the chorizo for a couple of minutes. It will render its own fat.
Add the diced vegetables and sauté until the onion has softened and the mushrooms have reduced non size. 8 to 10 minutes.
Add the stock, wine, tomato paste, worchester sauce, pepper, and bay leaves to the pan with the sautéed vegetables. Stir.
Add the vegetables and stock mixture to the lamb shanks in the dutch oven.
In the shanks aren’t covered in liquid, add some more wine or stock.
Put the lid on and put in the 160 degC oven.
Bake for 3.5 to 4 hours, turning the shanks once during that time.
Dice the carrot to be used with the diced meat into 5x5mm pieces.
Cut the hard base from the shimeji mushrooms and discard.
Sauté the carrot and shimeji mushrooms in butter until the carrot is starting to soften and the mushrooms are starting to brown. Set aside.
Remove the lamb shanks from the dutch oven and set aside to cool.
Strain the vegetables from the stock, reserving the stock.
In a saucepan, reduce the stock to 3/4 cup
When the lamb shanks are cool enough, remove all the meat from the shanks and give the bones and sinewy bits to the dog.
Using a knife on a large chopping board, dice the lamb into 3-5 mm pieces.
Mix the lamb with the carrot and shimeji mushrooms, and the 1 cup of reduced stock.
The mashed potato
Peel the potatoes and dice into inch square piece. (Excuse the reversion to imperial measures)
Add the potatoes to a large saucepan of cold water. Add the salt.
Bring the water to a boil, and boil for 15 minutes, or until the potatoes is done, ie a fork easily pieces them.
Drain the potatoes using a sieve, then leave to cool and dry.
Preheat the oven to 185 degC.
Melt the 20 g butter.
Mash the potatoes using a potato ricer (or mash them normally if you don’t have one yet).
Fold in the parmesan cheese, the truffle infused oil, half the melted butter, half the cream, and the pepper.
Add more of the melted butter and cream until it is of the right consistency.
Putting it together
Pour the lamb mixture into the base of a baking dish.
Layer the potato mixture over the top. Do it piece by piece, flattening some of the mashed potato on to a ladle, then sliding it off the ladle on to the top of the lamb mixture.
Sprinkle with the cheddar cheese.
Bake for 40 minutes at 185 degC.
Salad
Put the extra virgin olive oil, balsamic vinegar, and mustard into a jar or shaker. Shake well.