Preheat the oven to 200°C and place the bones in a deep roasting tray. Drizzle with a little olive oil and season. Roast for an hour turning the bones half way.
In a slow cooker, add the roasted bones and the rest of the bone broth ingredients. Cover completely with water, cook on high setting for 3-4 hours, then change to low setting and continue to cook for 12-24 hours. Throughout cooking, add more hot water as needed to keep all the ingredients submerged.
Once stock is ready, strain in a sieve and keep the liquid only.
Pour the stock into a heavy based casserole dish and bring to a boil. Cook the dumplings in the stock as per pack packet instructions. Add cooked spaghetti noodles.
Taste the stock and add soy sauce to season. Serve the noodles, soup and dumplings hot with a garnish of coriander, chilli and spring onions.