Place olive oil and butter in a skillet large enough to hold fish in a single layer. Place in oven 3 minutes, until butter melts.
Season fish with salt and pepper. Place fish flesh side down in prepared skillet. Bake 10 minutes, turning carefully once halfway through cooking time, until just cooked through. Remove from skillet; tent with foil to keep warm.
Add chopped bok choy and lemon peel to skillet. Stir to coat with oil in pan.
Place in oven 1 minute, until leaves are wilted and stems are warmed through.
Purée peppers and salsa in a blender for 30 seconds. Divide greens on four plates; top each with a piece of fish. Place a dollop of purée over each piece of fish.
In order to calculate Net Carbs of any whole food item, it's a simple calculation based off the Nutrition Facts panel:
Total Carbohydrates - (Minus) Dietary Fiber = (Equals) Net Carbs
For low carb products sweetened with sugar alcohols (ie: glycerin, maltitol, etc), refer to the Nutrition Facts panel of the product:
Total Carbohydrates - (Minus) Dietary Fiber - (Minus) Sugar alcohol = Net carbs
This reflects the fact that Dietary Fiber doesn't impact blood sugar levels. Sugar alcohols also have a negligible impact on blood sugar, they too are subtracted from total carbs to yield the Net Carb count.