Heat the oil in a saucepan. Add the curry and brown sugar. Add the pumpkin and onion and fry lightly. Add the stock, cover and simmer for about 20 minutes. Remove the pumpkin and onion from the saucepan and liquidise them with some of the stock. Add the liquidised vegetables back to the stock. Add the cream and heat gently. Season with salt and pepper. Pour into bowls and garnish with leek, capsicum and carrot.