In a large bowl, dissolve the yeast and a teaspoon of sugar in water.
Add the rest of the sugar, oil, and eggs, and stir well.
Add the flour a little at a time, mixing and kneading with your hands. The resulting dough should be heavy and thick, more similar to a shortcrust pastry dough than to a bread-like dough.
Let the dough rise for an hour, or until almost doubled in volume, then punch it down and add the raisins (previously soaked). As an alternative to raisins, children usually prefer their bulo with chocolate chips.
Divide the dough into buns and let them rise, placed on a baking sheet lined with parchment paper, for another hour. Meanwhile, preheat the oven to 356° F.
Brush the buns with egg yolk, sprinkle with sesame seeds (optional), and place them in the oven.
Bake at 356° F for 10-12 minutes, then at 320° F for another 5-10 minutes, until golden brown.