Preheat your cast iron loaf pans in an oven set to 425°F
In a mixing bowl combine flour, salt and mix.
Make a well in the center and add honey, yeast and warm milk kefir or buttermilk and let sit for 5-10 minutes for yeast to activate.
Add your mashed potato, put on the dough hook and let it combine on the first speed until it forms a ball. If it’s too dry, add a tablespoon water at a time. If it’s too wet add a tablespoon of flour at a time.
Form the dough into two oblong balls and pinch at the bottom.
Remove the hot pans from the oven and place the dough pinch side down.
Turn off the oven and leave it open to cool while you transfer dough from bowl to pans.
Place the pans back in the oven and let rise for 40 minutes.
If you are not using cast iron, rub your pans with butter or coconut oil and do not heat them. Leave in a warm, but off, oven for 1 - 1.5 hours.
Bake at 385°F for 30-35 minutes, depending on your oven and whether you preheated it. Loaves are done when they are brown and slightly pulled away from the pan.
Take out immediately and let cool a bit before slicing.