Step 1

Heat oil in a large frypan over medium-low heat. Add onion and a pinch of salt flakes and cook, stirring, for 20 minutes or until softened and lightly golden. Add sugar, vinegar and tomato paste and cook, stirring frequently, for a further 10 minutes or until caramelised and coloured. Transfer to a bowl and set aside to cool slightly.

Step 2

Wipe out pan, add bacon and place over medium heat. Cook, turning once, for 6-8 minutes until cooked to your liking. While the bacon is cooking, combine mayonnaise, garlic, mustard and herbs in a bowl. Spread herb aioli over the muffin bases. Top with lettuce, tomato, bacon, caramelised onion and sandwich with tops of muffins. Serve immediately.