Heat your oven to 200°C/Fan 180°C/Gas 6. Set a large roasting dish on the top shelf to heat up.
Peel your beetroot. Cut into 3 cm chunks.Tumble into the warmed tray with 1 tbsp oil. Season well. Roast for 20 mins.
Halve, peel and chop your onion. Add to the beetroot. Roast for another 10 mins.
Cut a few slices from your chilli. Blend the roasted beetroot with the chilli, your stock cube, 1 tbsp garam masala and the coconut milk. Trickle in 500 ml boiling water, or a little more, till the soup is as thick or as thin as you like it. Add more chilli or seasoning to taste.