Peel the onion and garlic cloves and cut them into small pieces. Press the juniper berries. Bring balsamic vinegar, beet syrup, bay leaf, vegetable stock, onion and garlic to the boil in a pot and simmer over medium heat for about 30 minutes until slightly syrupy.
Pass through a sieve and fill into two hot rinsed bottles with twist-off lids (each with a capacity of approx. 150 ml). Shelf life at least 4 weeks.