Rye Dinner Rolls with Crisp Tops

Stir together yeast, 1/4 cup warm water, and sugar in a large bowl and let stand until foamy, about 5 minutes. (If mixture doesn't foam, start over with new yeast.) Stir flours, salt, and remaining scant 3/4 cup water into yeast mixture with a wooden spoon until a soft dough forms. Turn out dough onto a well-floured surface and knead with lightly floured hands until dough is elastic and smooth but still supple and slightly sticky, 6 to 8 minutes. Form dough into a ball. Put dough in an oiled large bowl and turn to coat. Cover bowl with plastic wrap or a kitchen towel (not terry cloth) and let rise in a draft- free place at warm room temperature until doubled, 1 to 2 hours.