Grease a baking sheet.

Peel and dice the potatoes.

Boil the potatoes until tender.

Reserve 2/3 cup of the potato water.

Discard the remaining potato water.

Mash and sieve the potatoes.

Combine the mashed potatoes and potato water.

Let the mixture cool to lukewarm.

In a separate bowl, combine the flours, yeast, seeds, and salt.

Rub the butter into the flour mixture.

Gradually incorporate the potato mixture into the flour mixture.

Knead until a soft dough forms, using your hands if necessary.

Turn the dough out onto a floured surface.

Knead for 8-10 minutes, adding flour as needed to prevent sticking.

Place the dough in a lightly oiled bowl, cover, and let rise for about 1 hour, or until doubled.

Punch the dough down.

Turn the dough out onto a floured surface.

Knead gently for about a minute.

Shape the dough into a 7-inch oval loaf.

Place the loaf on the greased baking sheet.

Lightly sprinkle with whole wheat flour.

Cover the loaf and let rise for 30 minutes.

Preheat your oven to 400°F.

Using a serrated knife, slash 3-4 diagonal cuts into the top of the dough.

Bake for 25-30 minutes, or until golden brown.

Cool on a wire rack before slicing and serving.