Wash the chana dal a few times and soak in enough water for 30 minutes.
In a pan, boil 1 cup water with 1/2 tsp salt. Add the diced pumpkin to this. Cover and cook for 6-7 minutes, until pumpkin is tender, but not mushy. Drain and keep aside. Reserve the cooking liquid.
Drain the soaked chana dal, pressure cook with 1 cup water+1/2 tsp turmeric for 3 whistles and on sim (low flame) for 7-8 minutes.
In a pan, heat the oil. Add the panch phoron spice mix. If you don't have this, then use 1/2 tsp each of cumin and mustard seeds. Stir around the spices until aromatic, for around 30 seconds on medium flame.
Add the asafoetida, green chillies and onions, with a pinch of salt. Saute this for 4-5 minutes.
Add the tomatoes, turmeric, coriander powder and allow to cook on a medium flame, until tomatoes are pulpy. If too dry, add some of the cooking liquid reserved from cooking the pumpkin.
Once this is ready, add the cooked pumpkin and the chana dal.
Add amchoor powder, garam masala powder and bring to a simmer, mashing this a little with the back of the ladle.
Check the seasoning, adding any salt if required.
Remove into a serving bowl and garnish with fresh coriander leaves.