The only got a couple minutes in the parboil, and I think it was a good thing. They were good, there's room to improve, but I was happy for my first timeI'm with DB...I've done them dozens of times, and never parboiled.
We love roasted brussels sprouts, and making them on the grill is a snap.
We wash them and cut off the stem, then cut them in half, toss with olive oil, salt and pepper, and spread out on a baking sheet in a single layer. Roast at high heat, but without direct heat, until fork tender. There should be a fair amount of carmelization, which just adds to the flavor!
For a special treat, toss with just a trace of really good balsamic vinegar.