Svartsoppa (Swedish black blood soup)

Instructions

1. Pour the blood into a bowl with the vinegar and stir quickly to stop it clotting, then set aside.
2. Slice the onion and dice the carrots finely, then sauté them in the butter for 5 minutes.
3. Sprinkle with flour, stir for 1 minute, then gradually pour in the stock while stirring to get a smooth base.
4. Add the prunes, raisins, sugar and spices, then simmer for 30 minutes over low heat.
5. Off the heat, whisk in the blood vigorously, then return to very low heat for 10 minutes without letting it boil.
6. Adjust the seasoning with salt, pepper and a little vinegar, then serve hot with the cooked potatoes on the side.