Add all ingredients to a pot. Stir it together, bring to the boil, then reduce the heat and simmer for 10 minutes, until the raspberries break down.
Place a fine mesh strainer over a bowl or jug and pour in the mixture. Press the raspberries into the strainer to extract as much raspberry syrup as possible.
Allow the mixture to cool, then pour into a jar or bottle and keep in the fridge for up to 2 weeks.
To serve:
Fill a glass with ice and add 2 tablespoons of raspberry syrup, or more or less to taste (amount will depend on the size of your glass).
Top up with club soda and add a few fresh raspberries.
Notes
Make sure the drink syrup is fully cooled before adding it into a glass with sparkling water.
The level of sweetness depends on the person, so more or less syrup may be needed in each glass.
Homemade soda is best consumed immediately and tastes best if it’s mixed right before serving.
Variations
Add a tablespoon of heavy cream or coconut milk to make it a raspberry Italian soda.
Squeeze in some fresh lemon, orange or lime juice for a tangy citrus flavor.
Use flavored sparkling water for an additional layer of fruit flavor without adding more sugar.
For a deeper vanilla flavor, whisk in some vanilla bean powder to the syrup before adding to the glass.
Add in a dose of probiotics by replacing the soda water with your favorite kombucha.
Muddle in some fresh mint for a fresh summer flavor.