Heat sunflower oil in a large saucepan and soften onion, garlic, celery, and carrots for 15 minutes.
Add beef mince and cook for 5 minutes until browned while stirring.
Stir in tomatoes, tomato purée, beef stock, sugar, bay leaf, salt, and pepper.
Boil the mixture, then simmer gently for 20 minutes.
Mix flour, suet, salt, and herbs in a bowl.
Add 200ml cold water to form a soft dough.
Roll dough into 12 small balls with floured hands.
Place dumplings on top of the mince and cover with a tight lid.
Cook over medium heat for 18 to 20 minutes until dumplings rise.