Sauté the vegetables:
Heat olive oil in a large pot over medium heat. Add chopped onions and carrots, cooking for 5 minutes until softened. Stir in the garlic and cook for 1 minute.
Add the spices:
Stir in cumin, turmeric, paprika, and salt. Cook briefly to release the aromas.
Simmer the soup:
Add rinsed lentils and vegetable broth. Stir well, then bring to a boil. Reduce heat, cover, and simmer for 25–30 minutes, stirring occasionally, until the lentils are tender and the soup thickens.
Blend (optional):
Use an immersion blender to puree part of the soup for a creamy texture, or leave it chunky for a rustic lentil stew consistency.
Finish with lemon:
Stir in lemon juice before serving. Garnish with parsley or cilantro and a drizzle of olive oil.