How to Make It
Stir together blackberries, vinegar, water, sugar, and thyme sprigs in a medium saucepan. Bring to a boil over medium-high; reduce heat to medium-low, and simmer until blackberries have broken down, about 15 minutes. Remove from heat; cool 10 minutes. Remove and discard thyme sprigs. Transfer mixture to a blender. Remove center piece of blender lid (to allow steam to escape); secure blender lid on blender. Place a clean towel over opening in lid (to avoid splatters). Process until smooth. Pour pureed mixture through a fine wire-mesh strainer; discard solids. Stir in salt and pepper.