A Note about the Mold for Stretching Buñuelos: In Mexico, buñuelos are stretched over a cloth-covered olla, a round-bottom earthenware pot used frequently for cooking beans. Lacking a bean pot, use a deep up-turned bowl.
Prepare the “sponge.” In a small bowl, stir together the warm water, yeast and sugar; let stand 10 minutes until foamy (this lets you know the yeast is still active). Measure the flour into a the bowl of a stand mixer (or other large bowl if no mixer is available). Scoop out ½ cup of the flour and stir it into the yeast mixture. Cover and set in a warm place for an hour—the longer, the fuller the flavor. In fact, I typically let the sponge rest for an hour, then refrigerate it until the next day for maximum flavor development.
Make and portion the dough. Pour the sponge into the flour and add the soft butter. Beat the eggs with the salt and pour them in, too. Using the mixer’s dough hook or a large spoon, mix everything together. If using a mixer, knead for about 5 minutes, until the dough looks smooth. (If the dough is soft and sticky, work in enough flour to give it a medium-soft—not at all sticky—consistency.) If mixing by hand, turn the shaggy-looking mixture out onto a floured work space and knead for about 10 minutes, until smooth and elastic, adding as much flour as necessary to produce a medium-soft (but not sticky) dough. Transfer the dough to a very lightly greased bowl, flip over, cover with plastic wrap, and let the dough rise in a warm spot to double in bulk, about 1 ½ hours.
Scoop the risen dough onto a lightly floured work surface, lightly flour the top and press it into a rectangle. Cut into 24 pieces. Form into disks and place on a baking sheet lined with a floured towel. Cover lightly with plastic.
Stretch and fry the dough. Cover a round-topped mold (see note above) with a kitchen towel, making large, even pleats. Secure it at the bottom with a string or rubber band and rub flour thoroughly into the surface.
With a rolling pin, roll a ball of dough into a 6-inch circle. Lay over the mold and stretch into a nearly paper-thin 8-inch circle: Slip your fingers under the dough, thumbs still on the outside, and gently stretch the dough downward between thumb and fingers, letting it slip slowly through your grasp. Rotate the mold and gently stretch the dough again, continuing the process until you have a very thin round that’s about 8 inches across. The edge will be thicker, so make a pass around the dough, stretching short sections with both hands, to gently thin the edge. (When finished it will hang in ruffle around the mold.) Make ¼-inch cuts through the dough at 5 places, to allow steam to escape during frying.
In a large (10-inch), heavy, deep skillet, heat the oil to 360˚; it’s best to use a deep-fry thermometer and regulate the heat to keep the oil temperature as constant as possible. Carefully lay the stretched dough across the surface of the hot oil. Continually press it down with a pair of tongs, to expel the air and encourage hot oil to flow over the edges. After about a minute, flip it and fry for another minute, until thoroughly browned and crisp. Remove and drain on paper towels, preferably standing on edge to allow all the oil to drain off.
Stretch and fry the remaining balls of dough in the same fashion.
Prepare the syrup and finish the buñuelos. In a medium (3-quart) saucepan, combine 3 cups of water and the rest of the syrup ingredients. Boil over medium heat, stirring from time to time, until reduced to 1 ½ cups, about 30 to 45 minutes. The syrup should be as thick as honey at this point—thick enough to cool to a glossy-looking, no-longer-sticky coating. To test it, dribble some on a freezer-chilled plate, let it cool and touch it to make sure it’s not sticky. If it is still runny or sticky, simmer it a little longer.
Brush the hot syrup in a thin coating over each buñuelo. Let dry in a single layer until no longer very sticky, then stack the fritters on a tray and they are ready to serve.