Barbecue - Gourmet Burger

Ingredients

• 500 g Beef mince
• 1/2 Red onion chopped finely or grate coarsely
• 1 Beef stock cube
• 1 tsp Worcestershire sauce
• 4 Brioche burger buns
• 1 tsp Black pepper freshly ground
• 2 tbsp Red wine vinegar
• 2 tbsp Caster sugar
• 1/2 Red onion very finely sliced
• 8 Tomato vine sliced
• 80 g Lettuce leaves shredded
• 60 g Mayonnaise
• 1 tbsp Gherkin very finely chopped
• 2 tbsp Tomato ketchup
• 2 tsp American mustard
• 1 tsp Gherkin pickling liquid from jar