1: To make the dough, put flour, sugar, salt and yeast into a freestanding electric mixer fitted with the paddle attachment and mix to combine. In a small bowl, whisk together the warm milk, melted butter and eggs. Pour this liquid into the mixer and mix to form a dough. Knead in the mixer for 8-10 minutes, on a medium setting until soft and elastic.
2: Transfer the dough to a clean, lightly oiled dough and cover with a damp tea towel. Leave to rise in a warm place for 30-40 minutes until it is soft and slightly aerated.
3: Lift the risen dough out of the bowl and place on a lightly floured surface. Knock it back, then knead with your hands for 5-10 minutes. Return to the bowl, cover, and leave to prove for 30-40 minutes.
4: Meanwhile, make the filling. Heat a large, non-stick frying pan over a medium heat. Add the minced beef and dry-fry for about 20-25 minutes, stirring frequently, until it is nicely browned – it should have a crisp and crunchy texture.
5: Drain the crispy beef in a colander to remove any excess fat, then tip into a large bowl; set aside. Heat 2 tbsp of oil in the frying pan. Add the onions and cook over a medium-low heat for around 10 minutes until softened. Transfer the onions to the bowl with the beef.
6: Crank up the heat under the pan and add remaining 1 tbsp of oil. Tip the shredded cabbage into the pan and wilt quickly for a few minutes, stirring frequently. Add the cabbage to the beef and onions, then stir in the mustard, Bovril and caraway seeds. Season generously with salt and pepper.
7: After proving, knock back the dough on a lightly floured surface and divide into 12 equal pieces, shaping them into balls with your hands. Using a lightly floured rolling pin, roll each ball out thinly to a 14cm circle.
8: Divide the beef filling between the rounds of dough, spooning about 3tbsp filling into the centre of each round. Brush the edges lightly with melted butter and fold over to make semi-circles, as if you’re making pasties. Carefully press the edges together, then crimp with a fork to seal.
9: Lay runzas on 2 baking trays lined with baking parchment. Brush them with the remaining melted butter and leave to prove for a final 20 minutes. Meanwhile, preheat the oven to 210°C/Fan 190°C/Gas 7. Bake the runzas for 15-20 minutes until they are golden brown and crisp. Serve immediately.