Cashews – Pan-toasting raw cashews has the most superior flavor. But if you only have roasted cashews, that’s fine too. Just cook for around 1 1/2 minutes until they are lightly golden, and they smell nutty.
Do not use salted cashews, it will make the dish too salty.
Chicken – Thighs will yield a juicier result than breast. But breast will also work just fine. Consider tenderizing the breast the Chinese way. It makes it so much softer and juicier! (No need to do it for thigh).
Chili – A golden rule is the larger the chili, the less spicy it is (usually!) I’ve used large red cayenne pepper here which is not that spicy but still has a decent kick to it. You can omit or reduce the chili if you wish. If you want spicier, consider using Thai birds-eye chillis – BOOM! 🙂
Oyster sauce – This can be substituted with vegetarian oyster sauce, sold in some large grocery stores. It’s actually not bad.
Dark soy sauce – This soy has a more intense color and flavor than light soy and all-purpose soy. It stains the chicken an appealing mahogany color. If you use light or all-purpose soy, the dish color and flavor will not be as good! More on different soy sauces here, and when you can sub with what.
Fish sauce – Fish sauce is a traditional ingredient in Thai cooking and has more complex flavors than soy sauce. You can sub with more soy sauce, but the flavor will not be quite as good. (The oyster sauce still goes some way to compensate if you don’t use fish sauce, as it too is packed with umami!).