Sauté aromatics – In a large pot, heat olive oil or ghee. Add onion, garlic, and ginger, cooking until fragrant and softened (about 5 minutes).
Add spices – Stir in turmeric, cumin, coriander, chili powder, mustard seeds, and bay leaf. Cook for 1 minute to release flavors.
Simmer lentils – Add rinsed lentils and vegetable broth. Bring to a boil, then reduce heat and simmer for 25–30 minutes, stirring occasionally, until lentils are soft.
Finish – Remove bay leaf. Stir in lemon juice, salt, and pepper. Adjust seasoning to taste.
Serve – Ladle into bowls and garnish with cilantro or mint. Serve hot with bread, rice, or naan.