Bangers And Mash (Sausage With Onion Gravy)

Ingredients

• 2 tbsp butter
• 2 tbsp vegetable oil
• 2 medium onions (peeled and finely chopped)
• 2 tsp balsamic vinegar
• 2 tsp granulated sugar
• Half a liter of broth
• 4 tsp cold water
• 4 tsp corn flour (or cornstarch)
• Freshly ground black pepper
• Salt
• 2 potatoes (peeled and quartered)
• 110 grams of butter
• 6 tbsp milk
• 8 thick sausages