Texas barbecue brisket

INGREDIENTS

• about a 5kg/ 11 lb piece of beef brisket
• 500 ml/ 18 fl oz beef stock
• 1 tbsp sunflower oil
• 1 small onion , finely chopped
• 3 garlic cloves , crushed
• 500 ml/ 18 fl oz tomato ketchup
• 100 ml/ 3.5 fl oz Worcestershire sauce
• 75 ml/ 2.5 fl oz lemon juice
• 2 tbsp brown sugar
• 1 tbsp malt vinegar
• 2 tsp Dijon mustard
• 1 tsp crushed chilli flakes
• 1 tsp Tabasco sauce
• 1 tsp dried thyme
• 2 tbsp each chilli powder and mustard powder
• 1 tbsp each paprika , ground cumin, garlic powder, ground black pepper, caster sugar
• 1 bay leaf , crushed