Blackberry & lemon verbena soda

Ingredients

• 4 cups (1 kg) ripe blackberries
• 2 in (5-cm) strip of lemon zest
• 4 fresh lemon verbena leaves
• 1 cup (225 g) plus 2 tbsp granulated sugar
• 3 tbsp crème de mûre
• 1 L artisanal soda water

1. Rinse the blackberries under cool running water. Set them aside in a colander to drain completely.
2. In a large heat-resistant bowl, combine the lemon zest, lemon verbena leaves, and sugar. Use clean fingers to rub the aromatics and sugar together. Add the blackberries and gently toss to coat the berries with sugar. Cover the bowl with plastic wrap; double-wrap it to ensure that the seal will stay tight during cooking.
3. Bring a saucepan of water to a low simmer. Place the covered bowl over the simmering water to create a bain-marie. Be sure that the water does not touch the bowl. Cook the mixture for 1 to 1½ hours, or until the berries start to break down and steam pushes up on the plastic wrap. Occasionally check the water in the pan, making sure it doesn’t boil away. Remove the bowl from the heat. Keep the bowl covered and leave it at room temperature until cool. When cooled, place it in the refrigerator for at least 4 hours, or overnight.
4. When you are ready to work, remove the plastic wrap. Pour the berry mixture into a cheesecloth-lined strainer set into a large bowl and let it sit for 30 minutes to 1 hour. Let all the juices flow into the bowl. Do not press or push; you don’t want to force extra seeds or bits of the berries into the bowl. When all the liquid has strained through, remove the strainer from the bowl and discard the fruit.
5. Add the crème de mûre to the blackberry syrup and stir with a wooden spoon. In a 10-oz (300-ml) glass, pour 6 oz (180 ml) of the soda water. Add 2 oz (60 ml) of the blackberry syrup to the top of the glass and serve. The beautiful, velvety syrup will sit on top of the soda until you or your guest mixes it in.