Preheat oven to 450. Place the bok choy on a baking sheet and drizzle with oil, grated ginger, and garlic and season with salt and pepper. Roast for 10 minutes, then turn over and roast for 5 more minutes. Remove from oven, drizzle with the sesame oil and keep warm.
While bok choy is roasting, place tilapia filets on a foil lined baking sheet. Combine the miso, lime juice and brown sugar in a small bowl and spread on both sides of fish. After removing the bok choy from the oven, turn on the broiler and place fish in the oven. Broil for about 7 minutes or until fish is cooked through.
Serve with cooked brown rice and the lime wedges.
Notes
If you store your ginger in the freezer it is so much easier to grate!