Method
Sauté the diced onions in oil/butter until soft. Add flour and cook until the raw smell is gone.
Add rinsed red lentils and sauté for 2 minutes to coat them in the roux.
Pour in 6 cups of water and simmer on low heat until lentils are completely soft.
Use an immersion blender to process the soup until it is perfectly smooth and pürüzsüz.
Whisk milk, egg yolk, and lemon juice in a bowl. Temper with a ladle of hot soup.
Slowly pour the tempered mixture into the soup while stirring continuously.
Prepare the sizzling red pepper butter and drizzle it over the bowls before serving.
Notes
This soup was historically served with a side of toasted sourdough croutons or a sprinkle of dried sumac for extra zest. For the best experience, serve hot at 70-80°C (158-176°F) !