Prick sausages and cook in a non-stick frypan over low heat, turning a few times, until golden brown and cooked through. Remove from pan and set aside.
Return pan to the heat. Add the onions and cook over low-medium heat for 2-3 mins. Add the garlic and cook a further minute. Add the capsicum and oil and cook for 2-3 mins. Season with salt and pepper. Pour in the vinegar and cook for 1-2 mins until evaporated.
Slice each roll down the centre, but not the whole way through, and spread with a teaspoon of mustard. Place on an oven tray. Slice sausages lengthways. Fill each roll with 3 sausage halves and onion mixture. Sprinkle with cheese. Place under preheated grill for a few minutes to melt the cheese and serve.
Recipe courtesy of taste.com.au
Serving size 4