Wash and cut 500 grams of karela into medium-thick chips. Also, cut the onion into medium-thick slices.
In a mixing bowl, add the karela chips and salt. Mix well and let it rest for 10–15 minutes.
Meanwhile, in a mortar and pestle, add 3 tbsp peanuts, 3 tbsp white sesame seeds, and ¼ cup gathiya. Coarsely crush them.
Transfer the coarse powder to a mixing bowl. Add 1 tbsp coriander powder, 1 tbsp Kashmiri red chilli powder, 1 tsp roasted cumin powder, ½ tsp black salt, a pinch of salt, ½ tsp garam masala, 1 tbsp dry mango powder, 4 tbsp jaggery, 1 tbsp oil, and some coriander leaves. Mix well. The masala is ready—keep it aside.
The karela chips have been marinated with salt. Now add water and mix well. The seeds of the karela will be removed automatically.
Squeeze out the water from the marinated karela chips and place them on a plate.
Add 2 tbsp besan and coat the karela chips evenly.
Heat oil and add the besan-coated karela chips. Fry them on medium-high flame until they are slightly crisp and 90% cooked. Remove and place them on a plate.
In a pan, heat 4 tbsp oil. Add 1 tsp cumin seeds, ½ tsp mustard seeds, 1 tsp fennel seeds, a pinch of hing, and some curry leaves. Sauté them.
Add the onion slices and sauté on high flame until the onions turn slightly transparent.
Add 1 tbsp ginger-garlic-green chilli paste and sauté well.
Add ½ tsp turmeric powder and mix well.
Add the fried karela chips and mix well.
Now add the special masala and mix again. Cover and cook the sabzi on a low flame for 5 minutes.
Garnish with coriander leaves and serve the karela nu shak with roti and amras.