Any suggestions for a substitute for tamarind in the dressing?

Raisins, pureed with soy sauce, a touch of Worcester sauce, lemon juice.

pomegranate molasses in equal proportions

According to GourmetSleuth.com, for every 1 tablespoon tamarind paste you can substitute 1 1/2 tablespoon amchur powder, 1 1/2 tablespoon lemon juice powder or 1 tablespoon Worcestershire sauce.