Preheat oven to 450° F. with rack in centre of oven. Lightly brush a baking sheet with olive oil. Set aside.
Dry salmon and place on baking sheet (skin side down, if your salmon has skin on). Sprinkle with salt and pepper. Cut bok choy in half lengthwise. Place your bok choy on the baking sheet, cut side down and alternating the direction on every second one (it’s ok if your bok choy overlaps a little, to make it all fit). Brush bok choy with olive oil and season with some salt and pepper. If using, add a couple of orange slices to the baking sheet as well.
Place in pre-heated oven and roast for 15 minutes.
Meanwhile, combine sauce ingredients in a microwave-proof bowl (or in a small saucepan). Set aside.
Test salmon (use a fork to see if it flakes). Thicker salmon cuts may need another 3-5 minutes.
When salmon is almost done, place sauce in microwave for one minute. Stir to combine.
Remove salmon, bok choy and orange slices to a serving platter. Spoon warm sauce over salmon and drizzle a bit on the bok choy as well, if you like.