Pain au Potiron

Whisk together whole-wheat flour, all-purpose flour, yeast, salt, and vital wheat gluten in a 6-quart bowl, or a lidded (not airtight) food container.

Generously season pumpkin with pepper to taste.

Add water, oil, and pumpkin to flour mixture and mix without kneading, using a spoon or a stand mixer fitted with the paddle attachment. (You might need to use wet hands to get the last bit of flour to incorporate if you’re not using a machine.)

Cover dough (not airtight), and allow dough to rest at room temperature until it rises and collapses (or flattens on top), about 2 hours. The dough can be used immediately after its initial rise, though it’s easier to handle when cold. Refrigerate dough and use over the next 10 days. (The flavor will be best if you wait for at least 24 hours of refrigeration.)

Dust surface of refrigerated dough with flour and cut off a 1-pound (grapefruit-size) piece. Dust dough piece with more flour and quickly shape into a ball by stretching the surface of the dough around to the bottom, rotating dough ball a quarter-turn as you go.

Elongate dough ball into a narrow oval. Place loaf on a pizza peel prepared with cornmeal or lined with parchment, cover loosely with plastic wrap or an overturned bowl, and rest 90 minutes (40 minutes if you’re using fresh, unrefrigerated dough). Alternatively, rest loaf on a silicone mat or a greased baking sheet.

Preheat oven to 450° with a baking stone near middle of oven, with an empty metal broiler tray on any rack that won’t interfere with the rising bread, 20–30 minutes.

Just before baking, brush top of loaf with water using a pastry brush. Slash loaf diagonally with ½-inch-deep parallel cuts, using a serrated bread knife.

Slide loaf directly onto hot stone (or place silicone mat or baking sheet on stone if using). Pour hot water into broiler tray and quickly close oven door.

Bake loaf until richly browned and firm, about 35 minutes. (Smaller or larger loaves will require adjustments in resting and baking time.)

Cool bread on a rack before slicing and eating.