Cover the bowl and let it rest for 1 hour at room temperature.

💡 Pro Tip: Because the levain is stiff rather than loose, it can take a minute or two longer to fully disperse through the dough than a wetter starter would — don't rush this step, and scrape down the bowl if you notice small unincorporated bits clinging to the sides.

With the mixer still on the paddle attachment, add the 35g avocado oil and mix on speed 3 for 3 minutes, until the oil is fully incorporated and the dough looks glossy and cohesive rather than greasy or separated.

Switch to the dough hook, scrape down the sides and bottom of the bowl, and mix on speed 4 or 5 for 5 minutes. This is where your dough transforms — you're looking for a smooth, elastic dough that pulls cleanly away from the sides of the bowl and feels tacky but not sticky when you touch it. Because this is 100% whole wheat, don't expect the same glossy, windowpane-strong gluten you'd see in an all-purpose flour dough — whole wheat's bran naturally cuts and interrupts gluten strands, so a slightly shaggier, denser feel here is completely normal.

Perform a coil fold: with wet or oiled hands, lift the center of the dough up and let the ends fold gently underneath themselves, rotate the bowl a quarter turn, and repeat around all sides. This strengthens the dough's structure without deflating it the way a hard punch-down would.

Cover and rest another 30 minutes, then repeat the coil fold once more.

💡 Pro Tip: This is one of the biggest lessons I teach in my classes — bulk fermentation should be judged by how much your dough has actually risen, not by how many hours have passed. For this recipe specifically, let your kitchen temperature guide your target: if it's warmer than 75°F, aim for about a 30% rise before moving the dough to the fridge, since fermentation is already moving quickly and the dough will continue developing overnight. If your kitchen is cooler than that, let it rise closer to 50% before retarding it, since a cooler dough needs a bit more of a head start. Watching the dough's volume — and factoring in your kitchen's temperature — is far more reliable than following a fixed number of hours.

Turn the cold dough out onto a lightly floured surface. Shape it into a tight log or batard shape to fit your loaf pan — press it into a rectangle roughly the width of your pan, then roll it up firmly from the short end, sealing the seam as you go.

Lightly mist the shaped loaf with water or roll it in a bowl of water, then roll it in a shallow dish of rolled oats (or oat bran) to coat the top and sides. This is what gives the finished loaf that rustic, bakery-style crust.

Place the loaf, seam-side down, into a well-greased and lined 9x4x4-inch loaf pan.

⚠️ Watch Out: Because this dough is coming straight out of a cold, sluggish overnight rest, it can take longer to fully proof than you expect — sometimes 3 to 5 hours depending on your kitchen. Resist the urge to rush this step; an underproofed loaf will be dense and gummy in the center, even after a full bake.