Heat the coconut oil in a large pot or Dutch oven over medium heat. Add the diced onion and sauté for 5 minutes until softened and translucent.
Stir in the minced garlic, grated ginger, curry powder, ground cumin, and turmeric. Cook for 1 minute, stirring constantly, until highly fragrant.
Add the rinsed red lentils, canned diced tomatoes with their juices, vegetable broth, and full-fat coconut milk to the pot. Stir well to combine all the ingredients.
Bring the mixture to a gentle boil, then reduce the heat to low. Cover the pot and simmer for 20 to 25 minutes, stirring occasionally to prevent sticking, until the lentils are completely tender and the curry has thickened.
Remove the pot from the heat. Stir in the chopped fresh cilantro and season with salt and pepper to taste.
Serve the creamy lentil curry warm over steamed white rice, garnished with additional cilantro.