Excellent post re the cooking lessons with Az
I am glad that people are now seeing the light re "singeing"

After experimenting with big gas rings /high heat etc. over the past few years. see "Flaming Balti"
https://curry-recipes.co.uk/curry/index.php?topic=1104.msg9632#msg9632 posted way back in 2006.
I have found that using a domestic gas cooker still does the bizzo, although a bit messy with the splatter and smoke inside the house as the pics from the restaurant kitchen re Az will attest. Then...buy a splatter guard?!?!
So curry fans please don?t go off on the tangent and starting detailed discussion threads about the Megawatt output of burners etc? :

. Just think; ?If domestic cookers weren?t hot enough no houses would burn down with chip pan fires?.

Anyway, I have used the method below to make my Balti /Karahi style curries, which I and anybody else who has eaten them think meets the BIR taste test.
In your frypan/wok heat the oil hot and quickly sizzle your chosen spice mix until aromatic, just before burning add garlic/ginger mix this will spatter, keep cooking Add Onion, Green or Red peppers, fresh chilies, then just before everything starts to burn again add the base sauce a ladle at a time , add methi leaves (teaspoon or so) and half a tomato..Once bubbling add chicken pieces and turn down the heat and cook for a few minutes, just till the chicken is cooked through, do it too long and it gets tough. Don?t cook so long that the pepper goes soft .
Now take another pan, I use a small Karahi and add a tablespoon of oil "bog standard vegetable" . Heat till really hot "smokin" and tip your cooked curry into the pan, you may get fire, you will get sizzle, splatter and "the" smell.
Give a quick stir ..make sure your chicken is cooked.. garnish with fresh coriander and serve.
Instead of using only ground spices I have used meat masala pastes just after frying the spices but before adding the peppers & onions and it does add to the flavor, around a tablespoon for a small Karahi. I use Ashok meat Masalas brand paste here in Malaysia which is made in India, but I am sure you can get similar in the UK .
Re the bases I have tried a number of different bases and to be honest haven't noticed much difference between them. I think if you get that sort of sweet cooked onion flavour you are not far off. Again as shown in the Az base video, the base was simple.
I liked the addition in the Az cooking re the whole spice flavoured water and the home made garam masala. I will definitely have to give that a go.
Anyway Fleet 5 well done!!

Cheers
Jocko