Rinse lentils thoroughly and prepare all vegetables by chopping them evenly for consistent cooking.
Heat olive oil in a large pot and sauté onion, carrots, and celery until softened, then add garlic and cook briefly.
Stir in spices and toast them gently to enhance their flavor before adding liquids.
Add lentils, tomatoes, broth, water, and bay leaf, then bring to a boil.
Reduce heat and simmer until lentils are tender, stirring occasionally to prevent sticking.
Remove bay leaf, add lemon juice, and adjust seasoning before serving.