In a pan, add 1½ tablespoon of oil, and lightly heat it up for about a minute.
To it add ½ teaspoon of cumin seeds, and then ½ teaspoon of mustard seeds, and let them roast for a minute or so.
When the mustard seeds start crackling, add 10 curry leaves, 1 chopped green chilli, and 1 teaspoon asafoetida / hing. Mix everything together, and lightly roast them for 30 seconds or so.
Then add 1 cup of chopped onions, along with 1 teaspoon of salt, and saute on medium flame for 7-8 minutes, till the onions turn light brown in color.
When the onions are done, add 1 tablespoon of ginger garlic paste, mix it in, and lightly roast it for 1-2 minutes, just until the raw smell of ginger and garlic goes away.
Then add the spice powders (preferably all together, to avoid them from burning, so best to pre mix them and add) - ½ teaspoon red chilli powder, ½ teaspoon garam masala powder, ½ teaspoon coriander powder, ¼ teaspoon cumin powder, and ⅛ teaspoon turmeric powder. Here you can also add a splash of water and lower the flame for a bit to avoid the masalas from getting burnt.
Lightly roast the spices for about 30-60 seconds.
When the spices have been lightly roasted, add in ¾ cup of chopped tomatoes, and saute for 2-3 minutes, till the tomatoes have cooked down a bit.
Now to this add the pre-roasted chopped bhindi, mix it in, and saute for 5 minutes or so, till the bhindi is fully done. Here it is best to not cover the pan while cooking bhindi, so as to not incorporate any additional steam or moisture, which might make the bhindi slimy.
When done, turn off the flame, and serve hot. Bhindi masala goes very well with rotis / chapatis, and even as a side with dal rice.