Festive Caramelised Onions | Australian Onions

Ingredients

• 50 g butter
• 7 brown onions, thinly sliced
• ¾ cup brown sugar
• 80 ml red wine vinegar
• 2 tbsp balsamic vinegar
• 1 tbsp whole grain mustard
• 2 garlic cloves, crushed
• 3 star anise
• ½ tsp mustard seeds
• sea salt
• 2 small glass jars