Rye Dinner Rolls with Crisp Tops

Make dough:

1. 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.)
2. Stir flours, salt, and remaining scant 3/4 cup water into yeast mixture with a wooden spoon until a soft dough forms.
3. 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.
4. Form dough into a ball.
5. Put dough in an oiled large bowl and turn to coat.
6. 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.

Make rolls:

1. Punch down dough (do not knead).
2. Remove from bowl and fold into thirds like a letter.
3. Divide into 16 pieces and roll each piece into a ball, transferring to a parchment-paper-lined baking sheet and loosely covering with plastic wrap (or towel).
4. Let rise in a warm place until doubled, about 1 hour.
5. Lightly brush each ball of dough with some of egg white.
6. Gently lay a round of rye-crisp dough, egg-wash side up, on top of each roll. Bake rolls until golden-brown, about 20 minutes.
7. Cool to warm or room temperature.

Make rye-crisp tops while rolls rise:

1. Stir together flours and salt, then stir in water and oil until a dough forms.
2. Turn out dough onto a lightly floured surface and knead 4 or 5 times.
3. Divide into 16 very small pieces.
4. Roll out each piece on lightly floured surface to a thin round (about 2 inches; shape need not be perfectly round) and arrange in 1 layer on a sheet of parchment.
5. Beat egg white with a pinch of salt and lightly brush some of it onto rounds.
6. Let stand, uncovered, to dry slightly while rolls rise.

Assemble and bake rolls:

1. Preheat oven to 425°F with rack in middle.
2. Lightly brush each ball of dough with some of egg white.
3. Gently lay a round of rye-crisp dough, egg-wash side up, on top of each roll.
4. Bake rolls until golden-brown, about 20 minutes.
5. Cool to warm or room temperature.

Cooks' notes:

• Dough can be formed into balls and allowed to rise slowly, covered well with plastic wrap and chilled, 8 to 16 hours. Bring to room temperature while making rye-crisp tops.

• Rolls are best the day they are baked but can be frozen (first cool completely, then wrap well) 1 month. Thaw, then reheat on a baking sheet in a 350°F oven until warmed through, 5 to 10 minutes.