Heat a large frying pan over high heat. Add half the meat and cook until browned. Transfer to a heatproof bowl. Repeat with remaining meat.
Reduce heat to medium. Melt butter in same pan. Add the onion and paprika and cook, stirring, for 5 minutes or until onion softens.
Add the mushrooms and garlic. Cook until mushrooms are golden.
Add flour and stir for 1 minute.
Add stock, Dijon or worcestershire, tomato paste and meat. Bring to the boil.
Reduce heat to low and simmer, partly covered, for 45 minutes or until meat is tender.
Stir sour cream into beef mixture until just combined. Remove from heat.
Serve with angelhair pasta, top with fresh herbs.