1 pound young carrots, any color, trimmed, peeled 1 shallot, peeled, quartered 4 garlic cloves, peeled 2 red or green Thai chiles 2 sprigs tarragon 1 tablespoon black peppercorns 1 tablespoon coriander seeds 1 cup unseasoned rice vinegar 1 cup sugar 1 tablespoon kosher salt
Blanch carrots for one minute. Pack carrots, shallot, garlic, chiles, tarragon, peppercorns, and coriander seeds in a large heatproof jar.
Bring vinegar, sugar, salt, and 2 cups water to a boil in a medium saucepan, whisking to dissolve sugar and salt. Pour pickling liquid over carrots to cover. Let cool; cover and chill at least 24 hours.