Substitute raisins if you don't have currants.
Combine 3 cups water and rye berries in a saucepan; bring to a boil. Cover, reduce heat, and simmer 1 hour. Drain.
Combine 1 cup hot water and currants in a small bowl; let stand 30 minutes. Drain well.
Combine rye berries, currants, celery, parsley, 1/2 teaspoon salt, and pepper.
Combine 1/4 teaspoon salt, shallots, rind, juice, and vinegar in a small bowl, stirring well. Let stand 5 minutes. Stir in oil with a whisk. Pour shallot mixture over rye mixture; toss well to coat.