Mix flour, yeast, sugar, and salt in a large bowl.
Stir in warm water until the mixture forms a dough.
Knead the dough on a floured surface for 10 minutes until smooth.
Place dough in a greased bowl and prove for one hour until doubled.
Cream butter and lard together and divide into four portions.
Knead the proved dough briefly on a floured surface.
Roll dough into a 40cm x 20cm rectangle about 1cm thick.
Spread one portion of fat over the bottom two-thirds of the dough.
Fold the dough into thirds to create three layers of thickness.
Roll out to 40cm x 20cm again and repeat the spreading and folding.
Repeat the process twice more until all fat is used via four total rollings.
Preheat the oven to 200°C.
Roll out a final time, cut into 16 pieces, and shape into round buns.
Place on a tray and prove for 45 minutes until doubled.
Bake for 15 minutes at 200°C until golden-brown and cool on a rack.
Serve warm with butter and jam.