Festive Caramelised Onions

Ingredients

• 50 g butter
• 7 brown onion thinly sliced
• 3/4 cup brown sugar
• 80 ml red wine vinegar
• 2 tbsp balsamic vinegar
• 1 tbsp whole grain mustard
• 2 garlic clove crushed
• 3 star anise
• 1/2 tsp mustard seeds
• Sea salt
• 2 small glass jar