This is a without doubt my all time favorite dish, but having tried a lot of recipe's I'd got not very close tbh, until I happened upon a recipe on some curry forum or other. There are the usual 2 elements, the base gravy and whatever mix powder you prefer. I've used both Indian and Bangladeshi base gravy with good results, and mix powders recipes from various curry chefs. I use a bassar mix for this one because I like it, but I've used many other with good results. In this curry theres a third pre prepared element (not including the meat of course) which is detailed below and imho is the difference between a close second and the real deal, it is the garlic\chilli paste. The recipe for both the curry and the garlic\chilli paste are from a Bangladeshi curry chef who works in a Glasgow restaurant I'm told, but who and where was not disclosed. 

Garlic\Chilli sauce

Ingredients makes approx a jam jar full.

180 g of peeled garlic
25 g of peeled ginger
20 thin green chillies
1 tablespoon of mango chutney
1 teaspoon of lemon juice
1/4 teaspoon of vinegar
1 Tbsp oil

Method

Blend it to a smooth paste, job done.

South Indian Garlic Chilli Chicken

Ingredients

1/4 of a green pepper diced
2 tablespoon of melted ghee
1 tablespoon of garlic/ginger paste
1 heaped teaspoon of garlic chilli sauce
1 tablespoons of tomato paste cut 50/50 with water
1/2 tablespoon of mix powder
1/2 teaspoon of chilli powder
5 thin green chillies (seeds removed, chopped finely)
Pinch of salt
Good pinch of Methi leaves
1 teaspoon of coconut powder
250 ml of base gravy
1/2 tablespoons of sugar
1/4 a teaspoon of garam masala powder
1 good squirt of lemon dressing
2 tablespoons of chopped coriander.
10\12  pre cooked chicken bits ( smallish)

Method

Heat Pan (Moderate)
Add Ghee
Add half of the chopped green chilli's and pepper, cook for 2 minutes
add garlic\ginger paste cook for another two minutes
add tomato paste, mix in and cook through
add lemon, salt and combine
Turn heat up and add mix powder,sugar,coconut flour,chilli powder
fuse the spices.
add about 2 thirds of the base gravy, mix and reduce
Add the pre cooked chicken and Methi and mix in well
add the rest of the gravy, Lower the heat and simmer until the  sauce thickens
now add the garlic\chilli paste you made earlier, remainder of the chillies and garam masala
Simmer for 5 minutes, add coriander and serve.

The garlic\chilli sauce can be frozen, but I'm told the oil added to it preserves it?
The chillies I used in the garlic\chilli sauce are whole. A heaped teaspoon is a good starting point that isn't what non curry lovers would avoid, but you can add to your own taste, obviously. My curry nights consist of everyone wanting South Indian Garlic Chilli chicken and me trying to convince at least some people to try something else!
Maybe some of you can recommend adjustment? add ingredients?

Hello fellow curry addicts. I'm Ian, 45, Scottish and a big curry fan. Not quite a novice, but lots to learn about BIR dishes, my all time fav being "south Indian garlic chilli chicken", which is what lead me to learn how to cook BIR curry in the first place! I was sick n tired of take away AND restaurants trying to pap me off with "regional" excuse for their rubbish dishes, generally C\W tikka'd chicken! Best one I tasted was in a restaurant in glasgow called "Bombay blues", it was awesome. Since then I've had comparable dishes and truly pathetic. I have a recipe for what I have found to be the best effort yet, but...........I'm here to learn!