Heat the oven to 180C/160C fan. Put a large casserole dish on the hob over medium heat with a splash of oil.
Cut each sausage into three pieces and brown them in the casserole dish for about 5 minutes, turning occasionally. They do not need to be cooked through yet.
Add the chopped onion and diced carrots to the sausages and cook for another 5 minutes until the onion is soft and starting to colour at the edges.
Stir in the tomato puree and dried herbs, cook for a minute, then add the drained butter beans, chopped tomatoes and hot stock. Season with salt and pepper, bring to a simmer.
Mix the self-raising flour, suet and a pinch of salt in a bowl with just enough cold water to bring it together into a soft dough. Divide into 4 balls and place them on top of the simmering stew.
Put the lid on the casserole dish and transfer to the oven. Bake for 30 minutes, then remove the lid and bake for another 10-15 minutes until the dumplings are golden on top.
Serve in bowls with the dumplings on top. A slice of bread on the side is never a bad idea.