Heat the vegetable oil in a large pot over medium heat. Add the chopped onion and sauté until it becomes translucent.
Add the minced garlic and ginger to the pot.
Sauté for another minute until fragrant.
Add the curry powder, turmeric, cumin, coriander, and chili powder to the pot.
Stir well to coat the onions, garlic, and ginger with the spices.
Add the rinsed lentils to the pot and stir to combine with the spice mixture.
Pour in the diced tomatoes (with their juices), coconut milk, and vegetable broth. Stir everything together.
Bring the mixture to a boil, then reduce the heat to low.
Cover the pot and let the curry simmer for about 20-25 minutes, or until the lentils are tender and cooked through.
Once the lentils are cooked, season the curry with salt and pepper to taste.
Serve the lentil curry over cooked rice or with naan bread. Garnish with freshly chopped cilantro.