How to Make It
In a medium bowl, mix the blueberries with the sugar and vinegar. Let macerate at room temperature for 1 hour, stirring occasionally.
Preheat the oven to 200°. Spread the blueberries on a parchment paper–lined baking sheet and bake for 1 hour and 30 minutes, stirring occasionally, until thickened but still moist. Let cool.
In a blender, combine all of the ingredients, season with salt and puree until smooth. Strain the soup through a fine sieve into a large bowl. Cover and refrigerate for about 2 hours, until cold.
In a blender, combine the oil and herbs and puree until smooth. In a sieve set over a small bowl, strain the oil through a coffee filter or a double layer of cheesecloth.
In a medium bowl, toss the fennel and cucumber with the vinegar, sugar and salt. Let stand for 3 minutes. Add 1 tablespoon of the sweet herb oil; toss to coat.
Divide the blueberries into bowls and top with the fennel-cucumber garnish. Pour the soup around the bowl. Drizzle with some of the remaining sweet herb oil, top with fennel pollen and mint or anise hyssop flowers and serve.