Put yeast, sugar, salt, and oil into a mixing bowl along with lukewarm water and dissolve the yeast in the water.
Add chocolate chips and half of the flour into the mixing bowl and mix everything well. Now add the rest of the flour a little at a time until the dough is light and smooth. The dough should release from the sides of the bowl without becoming dry.
Let the dough rise for 30 minutes in a bowl under a shower cap or a piece of plastic wrap, or until it has about doubled in size.
Turn the dough out onto a work surface and divide it into 10 parts, rolling each piece into tight buns.
Let the buns rise again for 30 minutes on a baking sheet lined with parchment paper, under a dish towel.
Preheat the oven to 210 degrees Celsius (410 degrees Fahrenheit) using the fan setting, and bake the buns for 10 minutes on the lower rack of the oven with the fan on.
Let the buns cool on a cooling rack.