-Adjust oven rack to low position and heat oven to 425 degrees.
-Toss 1 bunch pearl onions with 2-3 TBS olive oil, 2 tsp sugar, salt and pepper in medium bowl.
-Transfer to a cookie sheet with rim.
-Roast onions until golden brown, about 30 minutes, stirring at 20 minutes and again at 25 minutes, adding 2 cloves chopped garlic.
-Meanwhile, bring 1 cup balsamic vinegar to boil; simmer over medium-high heat, about 10 minutes, until reduced to 1/3 cup, it should be a thin syrup.
-Put onions into a bowl, add reduced vinegar and 2 TBS parsley or basil and toss to coat.
-Serve hot, warm or at room temperature.