Heat 2 tablespoon of olive oil in a large pan (with a lid) over medium heat. Add onion, garlic and celery and saute until garlic is translucent and soft.
1 onion, 2 stalks celery
Add the cubed potatoes, carrots and season with a pinch of salt (the amount will depend on how salted your veggie broth is). Fry for about 1-2 minutes.
3 garlic cloves, 1 ½ cups cubed potatoes, 2 carrots, pinch of salt
Add the lentils, thyme, marjoram and veggie broth. Cover the pan with a lid and bring the mix to a boil. Then reduce heat and let simmer for about 25-30 minutes or until lentils are soft but not mushy. (see notes).
½ cup dry green or brown lentils, ½ teaspoon thyme, ½ teaspoon marjoram, 6 cups vegetable stock
Take the soup from the heat and let the soup cool for 5 minutes. Stir in the cheese.
⅓ cup shredded cheddar
Take out ¼ cup of the soup (without any veggies) and add it to a small bowl. Dissolve sour cream and add the mix back to the soup.
2 tablespoon sour cream
For a creamier soup, blend about ¼ of it with a stick blender (optional).
Taste and season with salt and black pepper. Serve garnished with fresh herbs.