Jerry
Completely agree on need to get onions right. Its Ok for finely chopped onions, as they will fry quickly. Look at Dipu's vid where after G/G, its almost throw everything in the pan. However, my favourite is a Dopiaza, and round my way, this is served with really chunky onion quarters (that would have been golf ball size before quartered). Now if these were fried in the standard TA cooking time, I reckon only the outer 3 layers will be cooked and the centre raw. I often wondered how such large on chunks could be so sweet and cooked through.
The answer really is the precooking. A mate of mine showed me how he "poaches" the onions in a gravy/water mix, for about 20 mins. They are allowed to cool in the liquor for another 15 mins. After that, they can be drained and set aside. This seems to have the benefit of softening and removing the bitterness. When introduced to the pan at cooking stage, it is for re-heating purposes, so in just before chicken/meat. Also, as well soaked, less likely to burn. So may be worth experimenting with poaching times and gravy/onion ratios(depending on onion size). This should have the benefit of avoiding burnings, reduce cooking time and have a more predictable result.