Spicy Beef Stir Fry

Last night I tried this amazing spicy stir fry.
Calls for:
1 Tbs cornstarch
3 Tbs dry Sherry
1 pound beef sirloin, thinly sliced against the grain into strips
Kosher salt and pepper
2 Tbs oyster sauce
2 Tbs sesame oil
3-4 Tbs peanut oil
1 inch piece of ginger, thinly sliced
2 cloves of garlic, smashed
5-7 dried red chiles, halved
1 small onion, thinly sliced
8 heads baby bok choy, halved
pinch of sugar
Cooked rice, for serving

Whisk the cornstarch with sherry, add beef strips, season with salt and pepper, then set aside for 15 minutes
Mix the remaing sherry, oyster sauce and sesame oil
Heat a wok or skillet over high heat until very hot, add 3 Tbs peanut oil, then the ginger, garlic and chiles; stir fry until fragrant, about 1 minute. Add the beef and cook, stirring occasionally, 1-3 minutes. Transfer the beef with a slotted spoon to the sauce mixture and toss.
If the pan is dry add more peanut oil, then add the onion and stir fry until soft, about 2 minutes. Add the bok choy and sugar, stir fry until wilted, 1-2 minutes. Return beef and any juices to the pan and stir to combine. Serve over the rice.