Classic Swedish meatballs

INGREDIENTS

• 400g lean pork mince
• 1 egg , beaten
• 1 small onion , finely chopped or grated
• 85g fresh white breadcrumbs
• 1 tbsp finely chopped dill , plus extra to serve
• 1 tbsp each olive oil and butter
• 2 tbsp plain flour
• 400ml hot beef stock (from a cube is fine)