Put all the marinade ingredients (except the chicken!) into a food processor and blend into a paste.Alternatively, grind in a pestle & mortar until smooth. Start with the toughest ingredient first and add one at a time. i.e. lemongrass then galangal, cilantro, chillies, turmeric, shallots then garlic. Then stir in the sugar, fish sauce, pepper and soy sauce
Using a sharp knife, make 2-3 deep slashes into each chicken drumstick. This will help the marinade permeate and create better flavour.Either in a bowl or a plastic resealable bag mix together the marinade and chicken. Make sure all the chicken gets a good coating. Cover the bowl or seal the bag and refrigerate for as long as you can. 4-5 hours minimum or 24 hours for the tastiest results.
Remove from the fridge about 1 hour before you plan to cook. Heat your BBQ grill or a hot oven grill.Grill the chicken for about 15-20 minutes, turning regularly - baste the chicken with some of the leftover marinade for added flavour and to keep the meat juicy (ensure this marinade cooks as it's had raw chicken in it). You want a nice char on the outside - it's all flavour!
Let the chicken rest for 5 minutes, then serve. I like to serve mine with a spicy dipping sauce like nam jim jaew (details and recipe for that below in the notes).
Notes
Dipping Sauce A great dipping sauce for Gai Yang is a Nam Jim Jaew dipping sauce - spicy, sour, sweet and salty... everything you need with a Thai dipping sauce - visit cookeatworld.com/crying-tiger-beef for the recipe.Alternative meats This marinade will work not only with chicken. Try marinating pork or beef too. thin cut pork chops or steaks work excellently. Beef steaks work excellently too. You can also make Thai Style satay skewers using thin pieces of marinated pork or beef threaded onto skewers. Cook on the BBQ grill.StorageFridge: You can keep leftover cooked Gai yang for 2-3 days in the fridge (covered). Eat cold or warmed in a 200ºc/400ºF oven for 8-10 minutes or until hot.Freeze: You can freeze the chicken at marinade stage for 2-3 month. Defrost thoroughly (in the fridge) before cooking as stated in the recipe.Freeze leftovers: You can freeze any leftovers for 1-2 months. Defrost thoroughly before reheating in a 200ºc/400ºf over for 8-10 minutes or until hot throughout.Leftover serving suggestionFlake leftover chicken into a bowl and mix with a little Nam Jim Jaew dipping sauce (see above for link). Then toss with some cooked and cooled rice noodles, crispy shredded lettuce, chopped cilantro or mint, shredded carrot, chopped cucumber and tomato for a delicious Thai noodle salad. Sprinkle with more Nam Jim Jaew and some chopped peanuts.