Heat the oven to 180’C
Mix the sausages in the marinade and roast in a pre-heated oven for 30-40 minutes (depending on their size) until they are golden
In the meantime, cook the potatoes in boiling salted water for 20-25 minutes until cooked through
Heat the butter and the oil in a separate pan and fry the onion on a gentle heat until soft and then add the sugar and the vinegar and simmer until the liquid has been absorbed and the onions are sticky. Add the gravy and simmer on a low heat until needed.
Cook your potatoes in boiling salted water until soft. When the potatoes are cooked, drain and then return to the heat for a few seconds to get rid of any excess liquid. Mash with the butter, milk and seasoning and when smooth and fluffy return to a low heat and beat vigorously with a wooden spoon for 1-2 minutes until really smooth
Remove the sausages and pour the excess juices into the gravy and stir well. Season the gravy to taste, plate all the ingredients and enjoy