Preheat oven to 160°C/140°C fan forced. Heat half the oil in a flameproof casserole dish over high heat. Cook the beef in 2 batches, tossing, for 2–3 minutes, until browned. Transfer to a bowl.
Heat remaining oil over medium heat. Cook onion, celery and carrot, stirring, for 6–7 minutes, until soft. Add garlic and rosemary. Cook, stirring, for 2 minutes. Add beef and wine. Simmer for 4–5 minutes until evaporated by half. Stir in tomatoes and vinegar. Bring to boil.
Cover and bake for 1 hour. Add cannellini beans and stir to combine. Cover and bake for a further 30–60 minutes until beef is tender.
Meanwhile, cook cauliflower in a saucepan of boiling water for 7–8 minutes until tender. Drain. Use a stick blender to blend with milk and horseradish until smooth. Season.
Divide the mash among serving plates and top with the beef. Serve with roughly chopped parsley.