For a quick meal, Mary Karlin, author of Mastering Fermentation, marinates shell-on shrimp (each shell split along the back), with a generous splash of the shrub--a sweet-tart infusion of vinegar and fruit--for about 20 minutes. Then she drains and cooks them in a lightly oiled cast-iron skillet, brushing them generously with this glaze, and serves extra on the side.
In a small frying pan, cook shrub and chile flakes at a low boil, swirling often, until reduced to 1/2 to 1/4 cup, 12 to 15 minutes. Sauce thickens at it cools.
