Heat oil in a deep skillet or large pot over medium-high heat. Add the onion and cook about 2 minutes, just until it starts to turn golden. Stir in the garlic and curry paste and cook about 1 minute, until the curry paste is fully incorporated.
Stir in the broth, coconut milk, pumpkin, tomato paste, and lentils. Cover and cook on medium-low heat about 15 minutes, until the lentils are cooked but not too soft. Stir occasionally. Taste and add salt and pepper to taste.
During the last 3-5 minutes of cooking, add 2 cups of baby spinach – allowing it to wilt into the curry.
Serve over rice, quinoa, cauliflower or your favorite base. If desired, add chopped roasted cashews and cilantro to the top for color, flavor, and crunch.