In large saucepan, warm olive oil and add garlic and onion. Saute, stirring 2-3 minutes. Add turmeric, garam masala, chili powder, and cumin.
Stir in tomatoes, lemon juice, vegetable stock, coconut milk, and bring to a boil.
Add lentils. Reduce heat to low and simmer, uncovered, for 20-30 minutes or until lentils are tender.
Serve warm, with naan bread. You can garnish with lemon slices and cilantro if desired.