Instructions

1. For the sausage: 
   Heat oil and 1 cup of water in a skillet over medium-high heat. Add sausage and cook, turning regularly for about 15 minutes, or until browned and cooked through. (Water will eventually evaporate, leaving the bit of oil to brown the sausage).
2. For the Mashed Potatoes:
   Cut the potatoes into 1-inch cubes and place them in a large pot. Cover the potatoes with cold water with enough salt so the water tastes quite salty. Bring to a boil, then lower the heat and simmer, uncovered, for about 10 to 15 minutes, until the potatoes fall apart easily when pierced with a fork.
3. Meanwhile, heat the milk and butter in a small saucepan, making sure it doesn’t boil. Set aside until the potatoes are done.
4. As soon as the potatoes are tender, drain. Mash the potatoes, then slowly whisk in enough of the hot milk/butter mixture to make the potatoes very creamy. Add the sour cream, a sprinkling of salt and some freshly ground pepper. Stir to combine. Taste for seasoning and add more, if necessary.
5. For the Onion Mustard Gravy:
   Melt the oil and butter in a large saucepan over medium-low heat. Add the onion and cover with a lid. Cook for about 10 mins or until the onions are soft and translucent. Add the sugar and balsamic vinegar to the onions and stir well. Cover with the lid again and cook another 5 minutes.Add the stock and boil gently uncovered for 5 minutes.
6. In a small bowl mix the cornstarch with the cold water to a thin paste. Pour a little of the hot gravy into the starch mixture and mix thoroughly. Pour the starch mixture back into the gravy, add the mustard, raise the heat to medium-high and boil for 10 minutes, stirring occasionally or until the gravy is slightly thickened. Season with salt and pepper to taste. Keep warm until ready to serve.