Heat the oil in a large frying pan and add the garlic, ginger, cumin, coriander seeds and chilli flakes. Stir-fry for 1–2 minutes, then add the beetroot. Fry, stirring gently, for 1 minute, then add the coconut milk, cardamom and lime rind and juice. Cook over a medium heat for 2–3 minutes.
Stir in the fresh coriander, season with salt and pepper and serve hot, warm or at room temperature.