Cottage pie · Ben Selby

Ingredients

• 500g lean beef mince
• 1 onion
• 1 large carrot
• 1 celery stick
• 1 tbsp tomato puree
• 1 tsp Worcester sauce
• 1 tsp mixed dried herbs
• 350ml hot beef stock
• 1 tbsp plain flour
• 900g potatoes
• Splash of milk
• Knob of butter