First, add the oil, mustard and cumin seeds to a frying pan. Allow then to sizzle to release their aromas.
Now add the onion and remaining spices and fry for 8-10 minutes until tender.
Add the garlic, salt and chilli and stir to combine and fry for a further minute.
Add the chopped tomatoes and tomato ketchup, stir and simmer for 5-6 minutes until the tomatoes are soft.
Now add the lentils, stock and chopped pumpkin and simmer covered for 20 minutes.
Add additional water as needed.
Finally, add the coconut milk/yogurt, season with salt and add garam masala