This bright summer berry sauce is not as sweet as you might imagine. The generous amount of lemon juice cuts nicely through the sugar and the lavender adds a subtle floral note. This sauce is best when made with peak-season blueberries, but you can easily use frozen fruit in the off-seasons. Note that the amount of sugar will vary depending on the sweetness and ripeness of your fruit.
MAKE AHEAD: The blueberry sauce can be refrigerated for up to 2 weeks.