Mix in ginger and garlic. After about 1 minute, add turmeric, garam masala, chili powder, salt, pepper, cumin, and curry powder, stirring and cooking for 2 more minutes.
Mix in the tomatoes, lentils, and broth. Bring the mixture to a boil, then lower the heat and simmer for 10-15 minutes.
Use an immersion blender to purée the mixture, partially blending it for a chunky texture or thoroughly blending it for a smooth soup.