Preheat oven to 400 degrees. Use Convection oven if you have one.
Trim the stems of the brussel sprouts if needed, and cut them all in 1/2, lengthwise. Toss them in a bowl with oil, salt, and pepper. Spread them out on a Sheet pan sprayed with pan spray. Pop in a preheated 400 degree oven. Cook for about 5 minutes. Add the orange juice and continue cooking another 5 minutes or so until the juice evaporates to be about 1/2 the amount. Remove from heat when they are cooked through, but not too soft. Stir to coat well with the orange reduction. Serve hot.