Using a deep skillet or pan, heat the olive oil over medium-high heat.
Once the oil is ready, add the onions and cook until it softens.
Add the sausage and tomato paste, then mix.
Cover with a lid and cook for about 4 to 5 minutes. Mix regularly to make sure that nothing sticks at the bottom of the pan.
Pour the cream and mix.
Place the lid back and bring korvstroganoff to a boil.
Adjust the heat to medium, then simmer for 2 more minutes.
Season with salt and pepper, then add the mustard.
Mix to combine evenly, then take the pan off the heat.
Serve sausage stroganoff with wild rice, if preferred.