Preparation

• Slice the onion into thin julienne strips and lightly sauté in a pan with a bit of oil or butter over medium heat for about 5 minutes, until soft.
• If any other ingredient needs to be cooked for the filling, prepare it in advance until it reaches the desired doneness, before filling the sandwich.
• Preheat the oven to 180ºC with heat from above and below.
• Use a sharp knife to remove the crust from the slices of sandwich bread, ensuring they are the same size.
• Overlap two slices of sandwich bread by approximately 2 or 3 cm to form a solid base.
• Firmly press the overlap with the rolling pin to properly fuse the seam, ensuring the bread remains flat and compact.
• Place the filling close to one of the long sides of the bread, leaving a margin of about 2 cm from the edge to facilitate rolling.
• Carefully roll the sandwich over itself to form a cylinder, starting from the side with the filling.
• Bake the sandwich in the preheated oven at 180ºC for 8 minutes, until it is slightly golden.
• Turn the oven to the broiler function.
• Finish the cooking with about 3 minutes under the broiler to achieve a golden and crispy surface finish.