750g whole piece beef fillet
60ml vegetable oil
300g onions, finely sliced
2 cloves garlic, crushed
2 teaspoons sweet paprika
400g button mushrooms sliced
80ml tomato paste
60ml dry red wine
1 tablespoon lemon juice
300g sour cream
1/2 cup milk
1/4 chopped fresh chives

Cut fillet into thin strips. Heat 2 tablespoons of the oil in medium pan; cook fillet strips, in batches, until browned then remove from pan and keep warm.
Heat remaining oil in same pan, add onions and garlic; cook, stirring, until onions are soft. Add paprika and mushrooms; cook, stirring, 2 minutes. Return beef to pan with paste, wine, juice, cream, milk; add chives; stir, without boiling, until heated through.