In a large bowl, combine the semi-strong flour and strong bread flour.

Add the instant dry yeast, salt, granulated sugar, and unsalted butter to the bowl.

Pour in the water (use lukewarm water in winter).

Gently dissolve the yeast in the water with your finger, then mix all ingredients by hand until a shaggy dough forms.

Transfer the dough to a work surface and knead by stretching and folding for 3 minutes.

Continue to knead by slapping the dough against the surface for another 2 minutes until it becomes smooth.

Shape the dough into a smooth ball.

Place the dough in a container, cover, and let it ferment at 25-30°C (77-86°F) for 60 minutes, or until it has doubled in size.

After the first fermentation, transfer the dough to the work surface and divide it into 5 equal portions.

Gently press down to release gas and round each piece into a ball.

Place the dough balls in a covered container and let them rest (bench time) at 35°C (95°F) for 20 minutes.

While the dough is resting, cut your preferred butter into five 8g portions for the filling.

Take out a dough ball and roll it into a teardrop shape about 18cm long. Repeat for all pieces.

Cover the shaped dough with plastic wrap and let it rest for 5 minutes.

After resting, take one piece and roll it out into a long strip about 45cm, gently stretching it as you roll.

Place an 8g piece of butter at the wider end of the dough strip.

Roll the dough once over the butter, then fold the sides inward to completely seal the butter.

Lightly brush the rest of the dough strip with salad oil.

Lift the dough strip to let it relax, then roll it up, starting loosely and tightening towards the end. Tuck the final end underneath.

Place the shaped rolls on a baking tray.

Spray the rolls with water to prevent them from drying out.

For the second fermentation, let the rolls rise at 35°C (95°F) for 50-70 minutes.

After the second fermentation, sprinkle the tops with your favorite salt.

Place the rolls in a preheated oven and spray with water about 15 times to create steam.

Bake at 210°C (410°F) for 12-14 minutes. If needed, rotate the pan halfway through for even baking.

Once baked, remove from the oven and let them cool on a wire rack. Enjoy!