Preheat grill (charcoal or gas) to medium-high.
In the meantime, cut onion and Shanghai bok choy in half lengthwise.
Drizzle 2 tablespoons of vegetable oil onto onion, Shanghai bok choy and scallions.
Place onion and Shanghai bok choy onto hot grill with lid closed and cook until slightly charred and softened, about 5-8 minutes.
Flip and cook other side to charred and softened with lid closed and also add scallions to grill, about 5-8 minutes as well.
Meanwhile, drizzle squid rings with 1 tablespoon of vegetable oil
Move onion, scallions and Shanghai bok choy to cooler place on grill. Over the high heat, grill squid rings. Cook 1-2 minutes until squid rings is a brighter white (from opaque white).
Flip squid rings until squid rings are a bright white, about 1-2 minutes.
Take all items off the grill.
Preheat frying pan with 1 tablespoon vegetable oil on medium-high heat.
Meanwhile, slice the onions, scallions and Shanghai bok choy lengthwise. Slice the kimchi into thin lengths as well. Add all vegetables to the hot frying pan.
Toss the vegetables in the frying pan after 1 minute. Add grilled squid rings to the frying pan.
Add soy sauce and kosher salt to taste. Quickly toss all items in frying pan once, remove from frying pan (so not to further cook squid rings) and serve immediately.