Crispy Ground Beef Sandwich

Ingredients

• 250g (9 oz) ground beef
• 1 tbsp Dijon mustard
• ½ tsp chilli flakes
• 1 tbsp Worcestershire sauce
• Salt
• pepper
• 1 small red onion, thinly sliced
• 125ml (½ cup) red wine vinegar
• 125ml (½ cup) boiling water
• 1 tsp salt
• 1 head of garlic, top removed
• 3 tbsp olive oil
• Pinch of salt
• 1 tbsp chopped fresh parsley
• 1 tbsp red wine vinegar
• 1 tsp Dijon mustard
• 1 tsp honey
• ½ tsp Italian seasoning
• 1 tbsp water