In a small dish mix baker's yeast, sugar and a tablespoon or two of lukewarm water. Set aside for 5-10 minutes, or until it bubbles up and starts to rise.
In a larger bowl, combine the yeast mix with flours, salt, 1.5-2 ounces of melted butter and 2 tablespoons sunflower seeds. Add about 25 ounces warm water, and start kneading. Knead until all ingredients are completely integrated and you have one, harder ball of dough. Cover and set aside in a warm place for 30 minutes to rise.
Knead a few more minutes, and set aside for another 30 minutes. Heat oven to 480F.
Sprinkle working area generously with flour. Take the dough ball out and split it in half.
Roll the first half out into a circle about 12 inches in diameter. Cut into 8 slices. Work each slice into a small ball, and then flatten a little bit until you get a disk. Place into an oiled pan. Follow with the remaining slices.
Repeat previous step with the second half of dough. Take a little bit of warm water and sprinkle onto each dough disk. Tap it in with your palm, and then sprinkle with remaining sunflower seeds.
Place the pan into the oven and bake for 10 minutes. Lower the temperature to 415F and bake for another 15 minutes.
Take out of the oven, paint with the remaining melted butter. Lift the breads onto their side and let cool for 15-20 minutes. Consume warm.
Please note you'll need an extra hour added to prep time for the bread to rise. You may need to bake these in two batches. Alternatively, halve the recipe.