Put the leek, onion, celery, and shallot in a medium dry saucepan. Cover and cook over medium heat, stirring occasionally, for 5 minutes. Stir in the roasted garlic, raisins, celery seeds, granulated garlic, and dried onion flakes and cook for about 1 minute. Add the remaining cup of the broth and simmer until the liquid is reduced by half, about 5 minutes. Stir in the tamarind mixture and cook for 5 minutes longer. Transfer to a food processor and process until smooth. If the mixture is too thick, add more broth, 1 tablespoon at a time, until the desired consistency is achieved. Stored in a sealed container in the refrigerator, Roasted Garlic and Tamarind Glaze will keep for 2 weeks.