Season beef with salt and pepper Heat 1 tbsp oil in large frypan, cook beef until just browned. Place in slow cooker. Heat remaining oil in same pan, cook garlic, onion and mushroom until just tender, season with salt and pepper. Add flour, stir until well combined. Transfer to slow cooker. In a large jug or bowl, mix liquid stock, tomato paste, paprika, worcestershire sauce and dijon mustard until smooth. Pour over beef. Stir well. Cook on low for 8 hours Stir through cornflour. Sauce will thicken. Stir through sour cream. Serve with rice and sprinkle with parsley.