Scrape the outer skin of the bitter gourds and slit lenghtwise. Scoop out the seeds and pulp. Rub salt and turmeric powder and leave aside for an hour. Gently squeeze the water out from the bitter gourds and keep aside.
Heat oil in a pan and fry the onions until brown. Drain the onions and keep aside. In the same oil fry the potatoes until tender and golden brown. Remove and set aside. Mix the potatoes with all the remaining filling ingredients.
Stuff the bitter gourds with this mixture. Secure tightly with thread and shallow fry until golden brown.
Remove the threads before serving.