Start by quartering the sweet potato, add to a pot of water, bring the the boil and simmer for around 12 minutes
Prepare the filling by adding the chopped onion to a frying pan with the olive oil and fry for 5 minutes before adding the chopped mushrooms, chopped chestnuts, dried herbs and chopped garlic
Fry on a medium heat for around 10 minutes
Drain the water from the sweet potatoes then add them to the pan with the filling and roughly mash together
Take off the heat and set aside to cool, you can add to tin foil to mix into the sausage shape to fill the pastry
Once the filling has cooled to room temperature prepare the pastry sheet, add the filling to the middle of the pastry sheet
Slice the edges of the pastry to create strips then overlap them to create a criss cross pattern, brush in the Tamari (or sub for melted butter and paprika) then place in the oven at 200ÂșC (fan) for 25-30 minutes or until crispy
For the gravy simply fry off the garlic, mushrooms and tamari, add in the cranberry sauce, pour over the stock and granules to thicken, whisk together before adding the cornflour to thicken & serve hot over the freshly baked wellington