You will need to make a paste or base. Put the garlic, ginger, with the roughly chopped coriander, green chilli, coconut cream, fish sauce lemon juice and sugar in to a blender and blitz till smooth- or use a food processor, stick blender, ninja or pestle and mortar. If you don't have these you could chop all ingredients till very fine. It is best as smooth as possible because you are making a homemade paste.
Put the chicken and the chopped onion, capsicum, bamboo stems and corn into a large bowl and pour over the coconut mix.
Mix everything together and sprinkle with salt. You can also do this straight into the baking dish if it is big enough. Stir it together well.
Spread all of this out well in yur baking dish, and make sure all the chicken is laying flat and is at least partly submerged. (I don't cut the chicken)
Put into the tray into a preheated oven and bake for 30 minutes. Take the tray out of the oven and move the chicken pieces around turning over and stirring.
Return to the oven and bake a further 30 minutes. For a fan forced oven check after 10 to 15 minutes. You can check if it is cooked by cutting or piecing the thickest part of the fillet. The juices should run clear and it should not be opink. A meat thermometre should measure 65C or 150 F
Taste the sauce, add more salt if needed and serve with steamed rice or noodles. This is also delicious served with extra herbs sprinkled on top. Add coriander leaves and Thai basil. You can take it to the table in the serving dish!