Rinse red lentils under cold water until water runs clear. Dice onions, carrots, and celery. Mince garlic.

Heat olive oil in a soup pot over medium heat. Add onions, carrots, and celery. Cook 5–6 minutes until softened. Add garlic and cook 1–2 minutes.

Stir in cumin, smoked paprika, coriander, turmeric, and black pepper. Toast spices for 30–60 seconds.

Add lentils and diced tomatoes. Stir to combine.

Pour in vegetable broth and water. Bring to a boil, reduce heat, cover, and simmer for 20–25 minutes until lentils are tender.

Optional: Use an immersion blender to partially blend the soup for creaminess, leaving some lentils whole.

Remove from heat, stir in lemon juice, and adjust seasoning.

Ladle soup into bowls. Garnish with parsley, drizzle with olive oil, and sprinkle red pepper flakes if desired.