BBC Food - Recipes - Corn on the cob with burnt-onion ketchup

Ingredients

• 2-3 tbsp vegetable oil
• 3 onions , peeled and sliced
• 2 bay leaves
• 150ml/5fl oz white wine vinegar
• 1 tbsp Worcestershire sauce
• 3 garlic cloves, grated
• 50g/1¾oz dark muscovado sugar
• 1 tbsp chopped salted anchovies
• 100g/3½oz butter , softened
• 1 tsp smoked paprika
• 1 tsp dried sage
• 1 tsp dried chilli flakes
• 1 tsp cracked black pepper corns
• 1 tsp table salt
• 1 tsp garlic powder
• 4 heads sweetcorn , husk and silk removed