Heat the oven to 180C/160C fan/gas 4. Toss the cauliflower, 1 tbsp of the oil and some seasoning in a roasting tin. Roast for 25-30 mins, then set aside.
Heat the remaining oil in a large saucepan and add the onion and cabbage. Fry gently over a medium heat for 10 mins. Add the ginger, garlic, spices and curry leaves and fry for 2 mins. Stir through the lentils and most of the cauliflower. Pour over the stock, bring to the boil, lower to a simmer and cook uncovered for 40 mins. Stir through the lime juice and season to taste. Ladle into bowls, top with the remaining cauliflower, toasted coconut and coriander and chilli, if using.