Rinse lentils under cold water. Dice the potatoes, and chop the onion, garlic, carrots, and celery.
Sauté olive oil in a spacious pot on medium heat. Add the onion, garlic, carrots, and celery. Sauté for 5-7 minutes, or until softened.
Stir in cumin, paprika, and thyme. Sauté the spices for 1-2 minutes to bring out their flavors.
Add the lentils, diced potatoes, vegetable broth, water (if needed), and bay leaf. Stir well and bring to a boil.
Lower the heat and allow the soup to gently simmer for 25-30 minutes, stirring from time to time, until the lentils and potatoes are soft and fully cooked.
Taste and add salt and pepper as needed. For a creamier soup, mash some of the potatoes or use an immersion blender to partially blend.
Ladle into bowls, garnish with parsley, nutritional yeast, or a squeeze of lemon, and enjoy!