1 1/2 pounds Brussels sprouts, trimmed and cut in half through the core
4 ounces pancetta, 1/4-inch-diced or bacon (optional)
1/4 cup good olive oil
Kosher salt and freshly ground black pepper
1 tablespoon syrupy balsamic vinegar (recipe below)
Preheat the oven to 400 degrees. Place the Brussels sprouts on a sheet pan, including some of the loose leaves, which get crispy when they’re roasted. Add the pancetta, olive oil, 1 1/2 teaspoons salt, and 1/2 teaspoon pepper, toss with your hands, and spread out in a single layer. Roast the Brussels sprouts for 20 to 30 minutes, until they’re tender and nicely browned and the pancetta is cooked. Toss once during roasting. Remove from the oven, drizzle immediately with the balsamic vinegar, and toss again. Taste for seasonings, and serve hot.
You don’t want to simmer the vinegar, so if you see bubbles turn it down. What you really want to do is VERY SLOWLY evaporate excess water to concentrate the flavors, so expect that this will go on for an hour or two depending on your volume.
Check and stir periodically. Keep an eye on the level in the pot for an idea of how far your liquid has reduced. As the thermal mass decreases with volume, you’ll likely need to lower the heat even further as the vinegar reduces.