Combine flour, yeast, sugar, 600 ml lukewarm water, and salt in a large bowl. Mix until a soft dough forms.
Let the dough rise in a warm place for 1 hour until roughly doubled in size.
While the dough rises, cook the diced bacon or ham with the diced onion over medium heat for 5-7 minutes until the bacon is cooked and the onion is soft.
Let the bacon and onion mixture cool to room temperature for about 10 minutes.
Preheat oven to 200°C (392°F).
Mix the cooled bacon, onion, and grated cheese into the risen dough.
With floured hands, divide the dough into roughly equal portions and place them on a baking tray lined with baking paper. Do not shape them finely—keep them rustic.
Bake for 20-30 minutes until golden brown. Spray with water or beer in the last 5 minutes of baking.