Gai yang really is just grilled marinated chicken - so it's nowhere close to being hard to make, and is universally liked. It's not spicy, and left overs are easy to use in sandwiches and salads. My friend Maria once diced up some left overs from this dish and tossed it up with the cabbage and cucumber that had been the garnish from the previous night's dinner, added fish sauce, sweet chili sauce and lime and it was a stunningly good salad. I seem to recall scoffing rather a lot of it.
In Thailand a whole quarter of a chicken is used, skinned, flattened out and wedged between split bamboo. This provides both the tongs and a 'handle' with which to eat it all in one. Brilliant. The bones in these pieces definitely add flavour and moisture to the meat while grilling, but boneless thigh fillets can also be used if you intend to chop it up to serve or if kids are involved and bones make it all too hard.
The marinade varies a lot from maker to maker and when I asked my Thai cooking teacher Yui about a recipe she said that everyone makes it their own way - it's not a dish with a recipe! Instead she gave me a list of ingredients people might use, but warned me to be careful of the sugar content because it makes it harder to cook the meat all the way through before the marinade burns. In that spirit I don't tend to measure the ingredients or get too worried if I am missing an ingredient or two, or if I toss in something new now and again.
Gai yang is ideally cooked over charcoal or wood fires to impart the characteristic flavour that brings South East Asia instantly to mind. In reality, I generally use the barbecue, or at a pinch the griller part of the oven.
Garlic - about 4 cloves, give or take.
Soy - I like the dark kind for this dish, a couple of tablespoons.
Pepper - ground black or white, about half a teaspoon.
Lemongrass - 2 stalks, white part only, roughly chopped.
Oyster sauce - 3 or 4 tablespoons.
Fish sauce - 1 or 2 tablespoons.
Tumeric - a small fresh grated knob or a few pinches of dried ground.
Ginger - a small fresh grated knob.
Palm sugar/white sugar/plum sauce - not too much or it burns.
(and remember don't worry if you don't use all these things!)
The marinade can be made in a mortar and pestle, but I usually smash it all up with the stab blender. Increase the amount of soy, fish or oyster sauce if there isn't enough liquid to make a runny paste.