Mix dry ingredients, potatoes, and sugar together in a large bowl or the bowl of a standing mixer.
Add 2 cups water with the mixer on. Let it mix together for a about 1 minute.
Gradually add the final cup of water and add more if necessary. The dough should stick to the bottom of the bowl but clean the sides and be sticky to the touch. If you add too much water, don't worry! Just add a bit more flour to get it back to the right consistency.
Knead 6-8 minutes in a mixer or 8-10 minutes by hand until the dough is smooth and elastic. Don't skimp on the kneading! This helps create the structure of the bread.
Let the dough rise (covered, room temperature) in the same bowl you mixed it in for 1 hour or until doubled.
Remove from bowl gently and form into 2 loaves. This is most easily done by creating a crease in the middle of the piece of dough with your palm and then folding the dough over the crease and pinching it together at the bottom, just imagine folding a piece of paper in half and gluing the bottom shut. Repeat this a few times until you have a smooth loaf shape. You may have to tuck the long ends in a few times as well.
Place in greased bread loaf pans and raise (covered, room temperature) 1 hour or until doubled.
Preheat oven to 375ºF.
Bake at 375º F for 25 minutes, remove from oven and brush each loaf with a tablespoon of butter.
Return to oven and bake 5-10 more minutes, or until golden brown. The internal temperature of the bread should read right around 200 degrees F.
Notes
I use standard size loaf pans, either 9x4 inches or 10x5 inches.I use instant yeast which is more potent than active dry yeast and doesn't need to be bloomed in water like active dry yeast does. If you’re using active dry, don’t worry, just put it in with your water for a few minutes instead of straight into the flour. If you forget which kind of yeast you have, it really won’t make too big of a difference in this recipe.The exact amount of water you will need for this recipe (or any baking recipe) can vary quite a bit. This is due to altitude, humidity, and weather. I live in an arid high-desert mountain climate, so often my readers need to less water if they live at a lower elevation with more humidity. If too much water is added, simply add more flour gradually until the proper consistency is reached.