Heat the oil in a large pot over medium heat. Add the onion and sauté for about 4 minutes, then add the garlic, ginger, and carrots. Cook for about 5 minutes, or until everything is fragrant and the veggies are starting to soften.
Add the garam masala, turmeric, cinnamon, cumin, and coriander and stir around for about 1 minute.
Add the lentils, coconut milk, pumpkin, and vegetable broth. Bring to a boil, then reduce heat to simmer for about 20 minutes, stirring occasionally, until the lentils are soft and the mixture is thick (you may add more broth or water if desired for a thinner consistency).
Stir in the lemon juice, salt, and pepper, to taste. Garnish with cilantro and yogurt/cream, if desired.
Serve warm with naan and/or cooked basmati rice. Enjoy!