Ingredients

• 1 1/4 teaspoons active dry yeast
• 1 scant cup warm water (105-115°F), divided
• 3/4 teaspoon sugar
• 2 1/4 cups unbleached all-purpose flour plus more for kneading and dusting
• 1/3 cup light or dark rye flour
• 1 1/4 teaspoons salt
• 1/4 cup unbleached all-purpose flour
• 2 tablespoons light or dark rye flour
• 1/8 teaspoon salt
• 2 tablespoons water
• 1 tablespoon olive oil
• 1 large egg white

Instructions

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. Form dough into a ball.
4. 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.
5. Make rolls: Punch down dough (do not knead). Remove from bowl and fold into thirds like a letter. 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). Let rise in a warm place until doubled, about 1 hour. Lightly brush each ball of dough with some of egg white. 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. Cool to warm or room temperature.
6. Punch down dough (do not knead). Remove from bowl and fold into thirds like a letter. 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). Let rise in a warm place until doubled, about 1 hour.
7. Lightly brush each ball of dough with some of egg white. 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. Cool to warm or room temperature.
8. Make rye-crisp tops while rolls rise: Stir together flours and salt, then stir in water and oil until a dough forms. Turn out dough onto a lightly floured surface and knead 4 or 5 times. Divide into 16 very small pieces. 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. Beat egg white with a pinch of salt and lightly brush some of it onto rounds. Let stand, uncovered, to dry slightly while rolls rise.
9. Stir together flours and salt, then stir in water and oil until a dough forms. Turn out dough onto a lightly floured surface and knead 4 or 5 times. Divide into 16 very small pieces. 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.
10. Beat egg white with a pinch of salt and lightly brush some of it onto rounds. Let stand, uncovered, to dry slightly while rolls rise.
11. Assemble and bake rolls: Preheat oven to 425°F with rack in middle. Lightly brush each ball of dough with some of egg white. 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. Cool to warm or room temperature.
12. Preheat oven to 425°F with rack in middle.