I added rosemary, red onion and small amount of red potatoes to make it more of a meal than just a side dish. The texture of the potatoes give the dish a nice complexity but should not be the star. Use twice as many sprouts as pieces of potato. I have tried it before with garlic cloves but I think the garlic was a bit too bold and took away from the fresh rosemary flavor.
Small red onion
Kosher sea salt and cracked black pepper
Place your roasting pan on the middle oven rack and then preheat the oven to 425. A preheated pan gives a better sear to the vegetables and the cooking time is greatly reduced.
Chop all the brown ends off the sprouts and cut the larger sprouts in half. Put all the yellow or dried leaves off and discard. Once you have chopped the sprouts you will have extra leaves that have fallen off, do not throw them away, just add them to the bowl with the other ingredients. Once they cook they will add a nice tasty crunch to the dish. Chop potatoes into cubes that mirror the size of the sprouts. Cut the ends off the onion, quarter and pull apart the layers. Pull the leaves off 2-3 sprigs of rosemary and put all the ingredients in a large bowl.
Pour enough olive oil into the bowl to lightly cover vegetables, add salt and pepper and lightly toss.
Carefully transfer ingredients to the hot pan in a single layer. Flip vegetables after ten minutes and then check every ten minutes until potatoes are tender and sprouts are fully roasted. Do not overcook or the sprouts will end up soggy.