Heat olive oil in a large pot over medium heat, then cook chopped onion, carrot, and celery until softened and translucent, about 5 minutes.

Stir in minced garlic, cumin, and smoked paprika, cooking for about 1 minute until fragrant.

Pour in rinsed lentils and vegetable broth, add a bay leaf, bring to a boil, then reduce to a simmer.

Cover and cook for 25–30 minutes, stirring occasionally, until lentils are tender.

Add fresh spinach leaves, stirring gently until just wilted, about 2 minutes.

Remove the bay leaf, stir in lemon juice, salt, and pepper to taste, then serve garnished with chopped parsley or cilantro.