Peel and slice carrots. Steam carrots till tender. If you don't have a steamer, put the carrots in a large pan with about an inch of water and once it begins to steam put a lid on the pan, reduce the temperature to low and let steam till slightly tender, yet crisp.
Mix cornstarch with about 1 tablespoon of orange juice and set aside.
Pour remaining amount of orange juice into a saucepan and mix in cornstarch mix and balsamic vinegar. Add butter. Cook on medium-low heat, occasionally stirring, until thickened and reduced, about 12-15 minutes .
Chop parsley. Toss glaze with carrots and diced parsley and serve.