Servings: 4 to 6

⅔ cup water ⅔ cup water
1 lemon, zest removed in wide strips, halved 1 lemon, zest removed in wide strips, halved
⅓ cup granulated sugar ⅓ cup granulated sugar
1 10–12-oz. bag frozen blueberries 1 10 to 12-oz. bag frozen blueberries
1 Tbsp. cornstarch 1 Tbsp. cornstarch

Bring lemon zest, sugar, and ⅔ cup water to a boil in a heavy medium saucepan, stirring until sugar disolves
Cook (don't stir) until a thin syrup forms, 6 to 8 minutes
Add blueberries and bring to simmer, reduce heat to medium; cook, stirring constantly, 2 minutes
Transfer 2 Tbsp syrup to a small bowl, add cornstarch, and stir until smooth
Add back to syrup; simmer until thickened, about 1 minute
Remove from heat, fish out lemon zest and discard
Squeeze in lemon juice to taste and let cool slightly