Lots of ways to cook this, I’d suggest you start with the recipe like this one:
https://www.splendidtable.org/story/2014/01/23/stir-fried-chicken-with-hot-basil
Feel free to adjust the quantities. I tend to like a little more garlic, onion and beans. I am also happy to substitute haricot verte for the oriental long beans. If you use the Thai chilies, it’s going to be pretty spicy. Feel free to replace those with one jalapeño or one Serano, if you want. Finding holy basil will be difficult, there are a couple varieties of Thai basil you can usually find in Asian markets.
If you don’t have a really hot fire, you might back off the quantities of the fish sauce and black soy sauce a little bit. Taste for seasoning at the end, I always seem to add a little more salt to season it properly. A little white pepper powder usually makes it into mine.
Try to use good quality Thai fish sauce and soy sauce. If you can’t find that, substitute Vietnamese brands. Chinese black soy sauce might work for the Thai black soy sauce but regular soy sauce won’t. Steer clear of any of the super salty fish sauces, they tend to run around 1200 to 1500 mg per tablespoon. I’m happier at under 1000. Red Boat fish sauce is a Vietnamese fish sauce that’s fairly readily available in stores, if you don’t have a good Asian market nearby.
I grind my own chicken from chicken thighs. Chicken breasts are not a good substitute and I wouldn’t use them in this dish.