Scoop out the seeds from inside, peel the skin and cut the pumpkin into medium sized cubes.
Wash them and keep aside.
Take a Kadai and add mustard oil in it. Put it on flame and let the oil cook till it reaches smoking point and fumes starting coming out of it.
Add fenugreek seeds and let them splutter for a while.
Add red chillies and saute for few seconds.
Add turmeric and red chilli powder and saute for just half minute.
Now add pumpkin cubes and toss properly.
Add 1 cup water, cover the kadai with a lid and cook on low to medium heat till the pumpkin is soft and tender.
Add tamarind water and jaggery. Cook for 3-4 minutes on high flame till the pumpkin becomes mashy.
Add salt to your taste. Mix.
Your ambal is ready. Serve it with rice and Rajma or Chane ki Dal.