In a bowl, combine besan, yogurt,turmeric, coriander & red chilli powder. Using a whisk, combine till a smooth paste is formed. Add water and whisk to make a lump free smooth mix. Let stand.
In a heavy bottomed pot, heat 1 tablespoon mustard oil till its slightly smoky. Add the okra and saute for 3-4 minutes till the skin they appear dark green and slightly blistered. No need to cook through. Take the okra out in a plate and set aside.
Add remaining 3 tablespoon mustard oil to the same pot. Let warm up so that the raw smell goes away. Remove from stove and let cool for a few seconds else spices will burn.
Add dried chilies hing and ginger to hot oil. Saute for 10-12 seconds. Next, add cumin, ajwain, fenugreek and coriander seeds. Return to a low stove. Saute for 10- seconds or so till spices begin to splutter and you smell their aroma.
Remove the pot from stove again and slowly add the besan-yogurt mixture we made. Keep mix simultaneously. Return the pot to medium stove. Now, gently keep stirring continuously until the mixture comes to a boil. Dont rush this else kadhi will curdle.
Once you see that the kadhi is starting to bubble, turn the heat to low, and let the kadhi simmer for about 15 minutes till it thickens slightly and is rich yellow in color.
Add the okra now along with sliced onion, add a little water(⅓ cup-½ cup) depending on the consisteny you like and let simmer for another 5-8 minutes till the okra is cooked through. Remove from stove and let stand.
Temper the Kadhi - In a small saucepan, warm up the ghee and add cumin seeds to it, when they splutter, add sliced garlic and red chiilies. Return to stove and cook for a minute or so till garlic is slightly browned.
Pour on top of kadhi. Serve!