Heat the oil to medium heat in a cast iron casserole. Then add the onion and fry for 3 minutes, then add the garlic and tomato and fry for further 5 minutes.
After add the diced carrots and red bell pepper. This is the sofrito, the base of the soup.
Rinse the lentils and add them to the sofrito, together with the coriander bouquet, salt, water and vegetable stock.
Bring it to a boil and lower the heat. Cook for 35 minutes or until the lentils are tender. Add boiling water if it needs it and check if it is properly seasoned.
Serve it in a bowl and garnish it with feta cheese and a dollop of sour cream. Enjoy!