Turn the oven to 200 degrees C fan.
Add your carrots, onions and ginger to a large tray lined with greaseproof.
Drizzle a little oil over the top and then add the turmeric, give everything a good tumble together, season if you wish and cover with foil.
Place the tray in the oven for 1 hour then remove and add the vegetables to a food processor along with the stock cube and a little water to loosen then blitz until smooth.
Pour the mixture into a saucepan with 500ml of water and bring to a gentle simmer. Check for seasoning and you're done!
