Stuffed Hamburger with Caramelized Onions

1. Mix all dough ingredients except flour

2. Add flour gradually and adjust based on consistency

3. Cover the dough and let it rest for 30 to 60 minutes

4. While the dough is resting, prepare the caramelized onions and meatballs

5. For the meatballs, mix all ingredients, shape into patties, fry on both sides until browned, and let cool

6. For the caramelized onions, slice onions into rings, sauté in a hot pan with a little oil until softened, add sugar and salt, then add butter and cook until color changes, and let cool

7. After the dough has risen, divide it into three equal parts and roll out each piece with a rolling pin

8. Add the cooked meatball, caramelized onions, and desired additional toppings like cheese, tomato, ketchup, and mayonnaise

9. Close the dough around the fillings, brush with egg yolk, and bake at 190°C for 15 to 20 minutes

Tips

1. Adjust the amount of flour in the dough based on its consistency to avoid it being too sticky or dry

2. The size of the meatballs can be customized, and this recipe yields about three hamburgers

3. Ensure all components are cooled before assembling to prevent the dough from becoming soggy