- 2 cups (500 milliliters) water
- ⅓ cup (65 grams) sugar
- 1 green apple, cubed
- ⅓ cup dried birch leaves
- 1 tablespoon lemon juice
- 1 cup (250 milliliters) water
- ⅓ cup (80 milliliters) vinegar
- 2 tablespoon (25 grams) sugar
- 4 cloves
- 2 cardamom pods
- 1 cup (150 grams) blueberries
- ½ cup (120 milliliters) Rhubarb Syrup
- 1 teaspoon soy lecithin
Bring the water, sugar, apple and birch leaves to a boil in a saucepan. Lower the heat to medium–low and let simmer until the sugar has dissolved and the apple is tender, 3 to 4 minutes. Turn off the heat and let the mixture steep with a lid on for 30 minutes.
Transfer the mixture to a blender, add the lemon juice and purée. Press through a sieve into a shallow baking dish and place the mixture in the freezer for 2 hours. After 2 hours, stir, break up and shave the granite with a fork every 30 minutes for the next 2 to 3 hours. When you have an icy crumble, pack it loosely in a closed container and store in the freezer until ready to serve.
Bring the water, vinegar, sugar, cloves and cardamom pods to a boil then lower the heat to medium–low and let simmer until the sugar has dissolved, 4 to 5 minutes. Place the blueberries in a mason jar or other airtight container and pour the warm liquid over them. Let stand on the kitchen counter until the mixture has reached room temperature, then place in the refrigerator. Let pickle in the refrigerator for 8 to 24 hours.
Pour the rhubarb syrup into a bowl, sprinkle with lecithin and use an immersion blender to whisk until foam forms. Tilt the bowl a little so that only two-thirds of the blender is immersed in the liquid, that way plenty of air gets in the mix to create the bubbles. The foam will stay firm for about 1 hour, so I recommend making it close to serving time.
Arrange the granita and pickled blueberries on plates and garnish generously with rhubarb foam.