Process onion, ginger, garlic, and green chilis into a paste.
Add 1 tbsp oil to a pot and add onion-ginger-garlic-chili paste to it, stirring frequently.
Add all spices to a small bowl and transfer to the pot, mixing well and making sure that spices don’t stick to the bottom. Cook until fragrant for a couple of minutes.
Add red lentils and butternut squash, combining with the spices for a few more minutes.
Add tomato paste, coconut milk, and water. Bring to boil, reduce to low heat, and cover. Let it simmer for 40-45 minutes, until the lentils are cooked and squash is tender.