Potato Dill Sandwich Bread

Why this recipe works This earthy-tasting bread is a sturdy sandwich loaf that’s packed with potato, and yet it has a wonderfully light, moist crumb. But if mashed potatoes are hefty and substantial, how do they contribute to a downy bread? As it turns out, the starches in potatoes work to dilute gluten-forming proteins, thereby weakening bread’s structural network and making it much more tender. We found that 8 ounces of mashed russet potatoes were the right amount to add to our dough for light slices that were still stable enough to hold sandwich fixings. After boiling and mashing the potatoes, we dried them out on the stovetop. This gave us control over how much liquid we were incorporating and ensured that we were not over hydrating the dough. We thought we’d boost the flavor of our bread with complementary dill; adding minced fresh dill during the last 1 minute of kneading lent the loaf a distinctive herbal flavor. In our testing, we had noticed that our loaves were tearing on the sides. This bread experiences a lot of oven spring (the rapid rising of bread after it’s placed in a hot oven), so we found that letting the loaf rise ½ inch above the lip of the pan ensured that its rise in the oven wouldn’t be so dramatic. Slashing the loaf before placing it in the oven was another foolproof way to eliminate tears by helping the loaf expand before its crust set. Don’t salt the water in which you boil the potatoes. The test kitchen’s preferred loaf pan measures 8½ by 4½ inches; if you use a 9 by 5-inch loaf pan, increase the shaped rising time by 20 to 30 minutes and start checking for doneness 10 minutes earlier than advised in the recipe.

MAKES: 1 loaf

RISING TIME: 1 hour 20 minutes to 2 hours

BAKING TIME: 45 minutes

TOTAL TIME: 3½ to 4 hours, plus 3 hours cooling time

KEY EQUIPMENT: medium saucepan, potato ricer, 8½ by 4½-inch loaf pan, pastry brush, instant-read thermometer

INGREDIENTS:

• 1 large russet potato (10 ounces), peeled and cut into 1-inch pieces
• 3 tablespoons unsalted butter, cut into 6 pieces
• 2⅔ cups (14⅔ ounces) bread flour
• 1½ teaspoons instant or rapid-rise yeast
• 1½ teaspoons salt
• 2 tablespoons minced fresh dill
• 1 large egg, lightly beaten with 1 tablespoon water and pinch salt

INSTRUCTIONS:

1. Place a potato in a medium saucepan and cover it with 1 inch of cold water. Bring the water to a boil over high heat, then reduce the heat to simmer. Cook the potato until it is just tender, which can be tested by inserting a paring knife into the potato and checking if it meets little resistance. This usually takes about 8 to 10 minutes.
2. Transfer ¾ cup (6 ounces) of the potato cooking water to a liquid measuring cup and let it cool completely. Drain the cooked potatoes and return them to the now-empty saucepan. Place the saucepan over low heat and cook, shaking it occasionally, until any surface moisture has evaporated, which takes about 30 seconds.
3. Remove the saucepan from the heat. Process the potatoes through a ricer or food mill, or mash them well with a potato masher. Measure 1 cup of the firmly packed potatoes (8 ounces) and transfer them to a separate bowl. Stir in butter until melted, and let the mixture cool completely before using. Discard any remaining mashed potatoes or save them for another use.
4. In the bowl of a stand mixer, whisk together flour, yeast, and salt. Add the mashed potato mixture to the flour mixture and mix with your hands until combined. It’s okay to have some large lumps. Attach the dough hook to the stand mixer and mix on low speed. Slowly add the cooled potato cooking water and mix until a cohesive dough starts to form and no dry flour remains, which takes about 2 minutes. Scrape down the sides of the bowl as needed.
5. Increase the speed to medium-low and knead the dough until it becomes smooth and elastic, and clears the sides of the bowl, which takes about 8 minutes. Reduce the speed to low, add dill, and mix until it is incorporated, about 1 minute.
6. Transfer the dough to a lightly floured counter and knead it by hand to form a smooth, round ball, which takes about 30 seconds. Place the dough seam side down in a lightly greased large bowl or container. Cover it tightly with plastic wrap and let it rise until it doubles in size, which usually takes 1 to 1½ hours.
7. Grease an 8½ by 4½-inch loaf pan. Press down on the risen dough to deflate it. Turn the dough out onto a lightly floured counter, with the side that was against the bowl facing up. Press and stretch the dough into an 8 by 6-inch rectangle, with the long side parallel to the counter edge.
8. Roll the dough away from you into a firm cylinder, keeping the roll taut by tucking it under itself as you go. Pinch the seam closed and place the loaf seam side down in the prepared pan, pressing the dough gently into the corners.
9. Cover the pan loosely with greased plastic wrap and let the dough rise until the loaf reaches ½ inch above the lip of the pan, and the dough springs back minimally when gently poked with your knuckle. This usually takes about 20 to 30 minutes.
10. Adjust the oven rack to the lower-middle position and preheat the oven to 350 degrees Fahrenheit. Using a sharp paring knife or a single-edge razor blade, make a ½-inch-deep slash with a swift, fluid motion lengthwise along the top of the loaf, starting and stopping about ½ inch from the ends.
11. Gently brush the loaf with the egg mixture and bake it in the preheated oven until it turns golden brown and the loaf registers 205 to 210 degrees Fahrenheit, which takes about 45 to 50 minutes. Rotate the pan halfway through baking.
12. Let the loaf cool in the pan for 15 minutes. Remove loaf from pan and let cool completely on wire rack, about 3 hours, before serving.