Heat the oil over a medium heat and add the onion, ginger and garlic, cook gently for a couple of minutes until beginning to soften. Add the curry powder and chilli flakes and cook for another couple of minutes until the spices are fragrant. Season well with salt and pepper.
Add the cauliflower and lentils to the pan and stir to coat then pour in the stock and coconut milk. Bring to a simmer and cook for 30 minutes until the cauliflower is soft and the lentils are breaking down.
While the curry cooks heat the 2 tablespoon oil in a frying pan and add the mustard seeds and garlic, cook for a couple of minutes then add the spinach, stir to wilt then turn off the heat. Serve the curry topped with the spinach, yoghurt and with rice and naan.
Nutrition information is an estimate and will vary depending on the ingredients used.