This will work in both the oven or slow cooker.
Take an oven prepared goose (greylag, canada), best if you have shot and prepared the bird yourself, and place on a house brick in cooker. Add 2 lemons to the birds cavity and 1/2 lb shallotts to the pan and cover with foil.
Leave on a medium heat for about 5 hours taking the foil off after 4 hours and remove some of the juices and put to one side.
After the last hour remove from the oven, throw away the goose and eat the brick with some of the reserved stock.