Sometimes, dishes are created with a great deal of thought, the repeated testing of recipes and the refining of ingredients and cooking technique. Other times, they spring from necessity - the cook needs to get dinner on the table using whatever ingredients they have to hand. This dish - which is sort of Thai-Chinese fusion - is one of the latter, but it's still delicious.
Soybean sauce is a Thai product, made of fermented yellow soybeans, which comes in a bottle or jar. You only need the liquid that floats to the surface; reserve the solids for other dishes.
Thai tempura powder (or mix) is different from Japanese tempura powder, and when fried, it makes a very crunchy crust. Thai people usually refer to it as Kogi or Gogi flour - the names of popular producers - even if they buy a different brand. Buy the plain tempura powder , not one of the flavoured varieties.
Put the black beans in a small bowl and add just enough water to cover them. Leave to soak for about 15 minutes, then drain. Put the Sichuan peppercorns in a small strainer and rinse with water, then put them in a small bowl, add water to cover and leave to soak for about five minutes before draining. Remove and discard as many as possible of the small black seeds from the Sichuan peppercorns. Put the black beans and Sichuan peppercorns in a bowl.
Roughly chop the bird's-eye chillies and add them to the bowl holding the black beans and Sichuan peppercorns. Chop the garlic cloves. Cut the onion and bell peppers into bite-sized pieces. Cut the spring onions into 5cm (2in) lengths.
Cut the chicken thighs into bite-sized chunks. Put the chicken pieces in a bowl and mix in the soybean sauce. Add the tempura powder and combine thoroughly. Mix the oyster sauce with 50ml of hot water.
Pour oil to the depth of about 10cm (4in) in a wok (if using a large skillet, add oil to the depth of about 4cm [1½ in]). Add four of the chopped garlic cloves, then place the wok (or skillet) over a medium flame. Cook the garlic in the hot oil until pale golden. Use a mesh strainer to scoop out the garlic then drain it on paper towels.
If using the stalk of green peppercorns, place it in the oil. Cook it briefly, just long enough to lightly scorch the the pepeprcorns. Take the stalk from the wok and drain on paper towels.
Stir the chicken, then place some of the pieces in the hot oil and fry until ithey're cooked through. Do this in batches; do not crowd the pan. Remove the pieces from the wok and drain on paper towels.
Pour off all but about 30ml (2tbsp) of the oil from the wok. Set the wok over a high flame, add the onion and bell peppers, then stir-fry until the peppers are blistered. Add the remaining garlic cloves and cook until fragrant, then stir in the Sichuan peppercorn/black bean/chilli mixture. Cook for about 30 seconds, stirring constantly. Add the chicken pieces and the oyster sauce/water and stir-fry briefly before mixing in the spring onion and basil leaves. Cook until the basil leaves are wilted then transfer the ingredients to a serving plate. Scatter the fried garlic on top, garnish with the stalk of green peppercorns and serve immediately, with steamed rice.