Rinse the lentils thoroughly, then place them in a pot with the vegetables and enough water to cover. Cook over medium heat until everything is tender.

Let the mixture cool slightly, then blend the lentils and vegetables using a blender or immersion blender until smooth.

Strain the soup, return it to the pot, and season with salt, cayenne pepper or chili powder, ground cumin, and a small cube of butter.

After adding the butter, the soup will reach the desired consistency.

Add the oats, bring the soup to a boil for a few minutes, then cover the pot and let it sit for about 10 minutes. Serve hot.