1. Finely chop the onion and garlic and fry in a little butter until transparent.
2. Add the rice and fry together with the onion and garlic for about a minute before deglazing with the vegetable stock. Set a little of the vegetable stock aside. Simmer at a low temperature for approximately 20 minutes until the rice is cooked.
3. Mix the yoghurt in a bowl with the egg yolk and flour. Beat the remaining hot vegetable stock into the yoghurt mixture and then pour this into the soup.
4. Finely chop the mint and fold in. Season the soup with a little lemon juice, salt and pepper.
5. Melt a little butter in a pan and add the red pepper flakes. Stir well and allow to bubble briefly.
6. Pour the soup into bowls, drizzle with the spiced oil and serve with toasted bread.