Place balsamic vinegar and honey in a small saucepan set tover medium-high heat. Bring to a boil. Simmer for 5 minutes. Stir in ketchup, garlic, oil and rosemary; reduce heat to medium-low and simer for 2 minutes. Stir in lemon zest and pepper. Coool completely.
To Freeze: Freeze in freezer safe container
To Reheat: Defrost. Use to glaze chicken under broiler or on BBQ.