Rinse the lentils thoroughly under cold water and set aside. Chop the onion, garlic, carrots, celery, and potatoes into evenly sized pieces to ensure uniform cooking.

Heat olive oil in a large soup pot over medium heat. Add the chopped onion and cook for 4–5 minutes until softened and translucent. Stir in the garlic and cook for 30 seconds until fragrant.

Add carrots, celery, and potatoes to the pot. Stir well and cook for 3–4 minutes. Sprinkle in cumin, paprika, thyme, salt, and black pepper, stirring to coat the vegetables evenly.

Add the rinsed lentils, diced tomatoes, vegetable broth, and bay leaves. Stir to combine and bring the soup to a gentle boil.

Reduce heat to low, cover, and simmer for 30–40 minutes, stirring occasionally, until lentils and vegetables are tender.

Remove bay leaves. Taste and adjust seasoning with more salt, pepper, or lemon juice if desired.

Ladle the soup into bowls and garnish with fresh parsley or cilantro.