Slice frozen K&N's Frankfurter Sausage and sauté on medium heat in a large skillet for 3 minutes, stirring continuously.
Add garlic and stir for an extra minute.
Mix in onions, tomato paste, mustard paste, salt and stir to combine flavours.
Add capsicum and mix together. Let simmer.
Mix in black pepper and set aside.
Split the sub rolls in half lengthwise. Hollow out the bread from the bottom side of each roll.
Layer bottom of the bread with lettuce.
Add cooked filling and serve hot.