How to Make It
Combine 1/4 cup vinegar, 4 teaspoons sugar, 1/4 teaspoon salt, and allspice in a dish; stir with a whisk. Add cucumbers; toss. Let stand 12 minutes, tossing once. Drain.
Combine Dijon, dry mustard, oil, remaining 1 tablespoon vinegar, and remaining 2 teaspoons sugar in a bowl, stirring with a whisk. Stir in dill and 1 1/2 teaspoons water.
Heat farro according to package directions. Divide among 4 bowls. Arrange chicken, cucumbers, and preserves over farro. Drizzle with mustard sauce; sprinkle with remaining 3/8 teaspoon salt.