Pour the yeast into a clean, small, shallow bowl. Add 1 teaspoon of the sugar and quarter cup of the warm water. Let the mixture stand for 2 to 3 minutes, then stir to dissolve the yeast completely. Place the bowl in a warm, draft-free place for 5 to 10 minutes or until the mixture looks foamy and has almost doubled in volume. Measure your flour into a mixing bowl, and make a well in the center of the flour. Pour the yeast mixture into this center depression, and then add the remaining water, sugar, and melted butter to the yeast. Mix the ingredients well with a spoon until a soft, spongy dough is formed. Cover the bowl loosely with a warm, damp cloth, and return it to the warm, draft-free spot until the dough again doubles in volume, about 45 minutes. Preheat your oven to 180ºC . When the dough has risen, place it on a lightly floured surface and divide it into six equal parts. With a lightly floured rolling pin, roll each part into a flat round about 1 cm thick. Place 2 or 3 rounds on each of two or three cookie sheets. Rub the surface of the rounds lightly with cool water, and sprinkle each with half teaspoon sesame seeds, or other topping. The water will basically help the toppings to adhere to the rounds when baked. Bake the rounds in the oven on the bottom rack for about 20 minutes or until the breads are a pale golden brown. (Bake breads in "shifts" if oven size does not allow entire recipe to be baked at once.) With a spatula, transfer the breads to a wire rack to cool. Breads will keep several days if stored in a dry, air-tight place.