Beat all the dough ingredients together with the paddle of a stand mixer, 4 to 5 minutes at medium-high, until the dough is smooth and a bit shiny. Use the lesser water in humid weather, more when it's dry.
Switch to the dough hook and knead about 7 minutes. The dough is soft and sticky and may not fully clear the bowl — that's right. (No stand mixer: a hand mixer can manage a single loaf; don't try to knead this by hand.)
Scrape into a ball, place in a greased bowl or bag, and refrigerate overnight (up to 24 hours).
Shape the cold dough into a loaf and settle it seam-down in a greased 8 1/2 x 4 1/2 or 9 x 5 pan.
Cover and rise until crowned about 1 inch over the rim — 2 to 4 hours, since the dough starts cold. Near the end, heat the oven to 350F.
Bake 25 minutes, tent with foil, then 15 to 20 minutes more, to a deep golden brown and 190F internal.
Turn out of the pan after 5 minutes and cool completely on a rack before slicing.
The crumb is soft and tender — closer to a homemade Wonder Bread than a chewy artisan loaf — and a little crumbly, so it sheds when sliced; cut it fully cooled and on its side.
Leftover plain mashed potato works; if you boil a potato for this, save the starchy cooking water for the dough liquid. Use the lesser amount of water in humid weather, the greater when it's dry. To make two loaves, keep the yeast at 2 tsp and double everything else. Wrapped at room temperature the loaf keeps 2–3 days, longer in cool dry weather.