Combine 1/2 cup warm water, yeast, and 2 teaspoons sugar in a large bowl and let proof.

Mix the remaining water, salt, bread flour, and flour into the yeast mixture.

Knead until smooth, adding more flour as needed to achieve a soft dough.

Cover lightly and let rise in a warm place until tripled in size (about 90 minutes).

Punch dough down and let rise again until doubled.

Punch dough down and roll into 2 cylinders.

Cut each cylinder into 8 rounds.

Lay flat, cover with a towel, and let rest.

Prepare the topping mixture by mixing the oil, poppy seeds, minced onion, and salt; set aside.

Pat each dough round into a flattened circle, slightly higher in the middle than at the outer edge, about 3 1/2 inches in diameter.

Place on a lightly floured surface and cover with a dry towel topped with a damp towel.

Let rise until half proofed (about 30 minutes).

Press the bottom of a shot glass about 1 inch into the center of each bialy to make a deep indentation.

Spread the topping mixture over the bialys and let rise for 15 minutes more until 3/4 proofed.

Preheat oven to 425°F while the bialys are rising.

Carefully transfer the bialys to 2 large ungreased baking sheets.

Bake on the upper and lower shelves of oven for 6 to 7 minutes; turn and switch the pans on the shelves so they bake evenly 5 to 6 minutes more.

Can be frozen.