Season beef, heat oil in large pan and brown osso bucco. Place in slow cooker.
Add purée, water, sugar, cider vinegar, coconut aminos, balsamic, star anise, chillies, ginger and mandarin peel to pan, and bring to a boil.
Add the sauce to your crockpot, season with salt and pepper, and cook on low for 6-8 hours.
When stew is nearly ready, put a pot of water on to boil, and add diced sweet potato and carrots.
When soft (about half an hour), drain sweet potato and carrots and mash with a splash of coconut milk.
Serve stew on top of sweet potato and carrot mash, and top with deep fried onion (optional).