In a medium bowl, add 1 cup of flour, yeast, and 1 cup of slightly warm water, about 110° F and 115° F; use a kitchen thermometer for accuracy. Using a rubber spatula, mix to combine. Let the yeast mixture sit for about 15 minutes until it doubles in size.

Combine the remaining flour, sugar, and salt in the center of a clean work surface or a 30 qt. standard weight mixing bowl. Make a well in the center of the flour mixture about 4 inches wide.

Add the yeast mixture into the well; use your hand to incorporate the dry mixture into the wet mixture a little at a time until somewhat incorporated. Next, pour in the warm water while using your hand to combine the ingredients into a homogeneous mixture.

Knead the dough until you have a smooth and elastic dough that releases from the work surface or the bowl, about 10 to 15 minutes. If you find your dough sticking to your work surface after kneading it, you can try drizzling a bit of oil rather than flour to help it release itself from the surface.

The oil will create a barrier between the dough and the surface, making it easier to work with. Just be sure to use a light hand when adding the oil, as too much can make the dough greasy and difficult to work with. When the bread dough has been kneaded to the perfect consistency, cover it with a clean kitchen towel and rest for at least 30 minutes or until it’s nearly doubled in bulk.

Lightly flour your hand and roll one end of the dough up in the center, and using your fingertip, press into to form a deep indentation. Roll the other end and press ends together to seal. Bring both sides together and roll into ovals to resemble a football ball. Repeat with the remaining pieces of dough. Slash each roll, about ½-inch deep, with a sharp knife lengthwise, stopping ½-inch from each end (these cuts will open up during baking).

Set on one of the ungreased baking sheets. Repeat with the remaining pieces of dough. Leave 1 inch of space between each bread, then put in a warm place, covered, and let rise until doubled, about 30 to 40 minutes until doubled. Preheat the oven to 450 degrees F and position your oven racks with one on the bottom and the other in the middle.

Place an oven-safe (non-glass) bowl or pan on the bottom rack. Simultaneously, slide the baking sheet with the bolillos onto the middle rack while carefully throwing the 4 ice cubes into the bowl on the bottom rack. (If you have a glass window on your oven, place a towel over it when spraying cold water or throwing the ice in, hot glass can shatter if cold water or iced  touches it.)

The cold water or ice will create a burst of steam that will give your Bolillos a nice crispy crust. Quickly shut the oven door, so no steam escapes, and bake the Bolillos for 15 - 20 minutes or until the Bolillo, is golden brown and hollow when tapped.