Rub the licorice, bicarbonate of soda and the 4 tablespoons of water in a bowl for 2 minutes with your fingers. Cover and set aside for 1 hour.
Pour the bowl contents into a double- or triple-layer of clean cheesecloth (15 x 20 cm [6 x 8 inches]). Twist the cloth and knot it to form a sort of tea bag.
Hang the cheesecloth tea bag in a pitcher with the 1 litre (4 cups) of water.