Chop brussel sprouts in half. If they are particularly large, you can slice them into quarters. The goal is to have bite size pieces for roasting.
Line a baking sheet with a piece of aluminum foil. Preheat oven to 375 degrees (F).
Spread brussel sprouts on baking sheet in a single layer. Toss brussels sprouts with olive oil, salt, and pepper.
Roast in the oven for 20-25 minutes. They are done when they start to caramelize.
In the meantime, heat balsamic vinegar in a small sauce pot. Bring to a simmer and allow to cook until the liquid is reduced by roughly half. Be careful not to overdo it, or you will get a sticky mess!
Remove brussel sprouts from oven, and toss with balsamic reduction. Roast for additional 2-3 minutes. Serve hot!