Melt butter and heat oil in a pan. Season the meat and cook in the pan till the meat is coloured slightly, turning from time to time. Add the onion, reduce heat and cook for about 5 minutes. Add the flour, paprika and caraway, mix well and cook for 2 – 3 minutes. Add the puree mix in well then add the hot stock, stirring well. Bring to a gentle boil and cook for 20 minutes. Fifteen minutes into the cooking add the potatoes which have been peeled and cut into halves or thick slices, depending on their size. Adjust the seasoning with salt & pepper and lemon juice if needed.