Preheat the oven to 400°F.
Trim the stem off the Brussels Sprouts and remove any discolored or damaged outer leaves. If the bulbs are medium to large, cut them in half lengthwise, if they are small, you can leave them whole. Make sure you keep any green leaves that fall when trimming, add these to the pan, they crisp up nicely.
Put the Brussels Sprouts on a sheet pan large enough to hold them in a single layer. I used a 12"x17" pan. Add the pancetta.
Add the olive oil, 1 teaspoon salt and pepper and toss with your hands until all the veggies and meat are coated nicely. Start with 3 Tablespoons of oil and add the 4th if you think there isn't enough oil. Spread the Brussels Sprouts into a single layer.
Roast for 20 to 30 minutes until the Brussels Sprouts are tender and the pancetta is crisp. Stir once during roasting.
Put the Brussels Sprouts mixture into your serving bowl, drizzle with the balsamic vinegar, and toss. Taste and add the additional ½ teaspoon salt if necessary to your taste.