Heat the oil in a large pot and add the veggies (garlic, onion, celery and carrot). Cook over medium-high heat until golden brown, stirring occasionally. If you don’t eat oil, use some vegetable stock or water instead.
Add all remaining ingredients except the salt and pepper. Stir.
Increase heat and bring to simmer. Cover with a lid, reduce heat to medium-low and simmer for about 40 minutes or until lentils are soft.
Finally, add the salt and pepper and stir.
To thicken the soup, use an immersion blender and do 3-4 quick pulses. You could also transfer 1 cup (250 ml) to a regular blender and blend, then transfer back into the pot. This step is totally optional.
Serve immediately (I topped my soup with some chopped fresh parsley) or keep leftovers in an airtight container for about 5-7 days.