Sous vide & deep fry ? double-fry ? chinese velveting & deep fry ?

@Coco et Cocoa Using the egg whites with the velveting method followed by a single fry gives me a lighter and more shattering thin texture.
thanks for your invaluable advice! (:

You recommended the double fry method. I have read from some sources that frying at a low temperature can cause the chicken to be greasy due to a higher oil absorption. Is this true ?

What temperatures and the duration will you recommend for the first and second fry?

Currently, based on a recipe I found online. I have used 190°C for 1 min followed by 160°C for 4min in one single fry.

@coco et cocoa thanks so much for your uber detailed reply!

We tried out these 2 cooking methods using a mixture of premix tempura batter and tapioca starch.

method 1: velveting + sous vide 1h 65°C + Deep fry 190°C 2min
method 2: velveting & double fry 1st time 160°C 2min, fry 2nd time 180°C 2min

method 1 results: texture of the chicken wings was more tender than method 2. shattering thin & crispy crust. remain crispy after it remains cool.

Method 2 results: meat texture is tender but not as tender as method 1. crispy bits here and there and slightly craggy.

Qns:
Did we perhaps over cooked the wings in method 2, thus it was not as tender as the wings in method 1 ?

Does it make a difference using just the egg whites or using the whole egg with the flour ?

Absolutely not. Sous vide is good for a couple of things when it comes to meat - 1. evenly cooking extremely lean cuts to prevent overcooked dryness say, in a tenderloin steak or chicken breast, and 2. converting tough collagen in connective tissue into rich, supple gelatin over long low-temp cookery for otherwise tough cuts like short ribs and pork belly. Now chicken wings are small and very fatty, so 1. doesn't really apply. Then perhaps 2. applies? Since the skin (where most of the collagen is anyway) of the chicken is very thin, and readily expands and crisps (due to water evaporating out of the skin at high temperatures), toughness of the skin is not a problem if you skip sous-vide. The tiny muscles in the wings definitely do not need much structural breakdown either, so all in all, sous vide is great, but wouldn't make much of a difference with wings.

On the other hand, double-fry is definitely a good idea as you essentially set up the skin and cook the interior to doneness at a lower frying temperature first (so it doesn't burn before the inside cooks). Then as second fry at a high temperature to get the skin extra crispy and nicely colored.

Chinese velveting is not primarily used for crisping the wings, but improves flavour and tenderness. The rice wine breaks down the proteins a little to give it a tender, snappier texture and also adds flavour. Aromatics like ginger, garlic, and star anise are purely for flavouring. The cornstarch, however will help you get some extra crispy-bits as they gelatinize and dehydrate in the hot oil. Combined with the egg whites which form a sort of batter with the cornstarch this batter forms a thin protective coating over the chicken, and when fried produces a lighter, airier crispness.

If I were you, I'd combine Chinese-velveting with a double-fry.