In a small pan, heat the vegetable oil over medium heat. Add the onion, cooking until it’s slightly brown, about 7 minutes. In a large bowl, thoroughly combine the sausage meat, cooked onion and two eggs. Season with salt and black pepper to taste.
Heat the oven to 205 degrees Celsius. Sprinkle flour on a work surface, and roll out the puff pastry into two 20-by-25 cm rectangles. Cut into four strips, and let them rest in the fridge for 10 minutes.
Spray two baking sheets with cooking spray and place the cold pastry rectangles on them, two on each. Scoop the meat mixture onto the rectangles, forming a long strip in the center. Beat the last egg in a small bowl, and brush on the edges of the pastry.
Fold the pastry over the meat filling, enclosing it, and flip so the seam is on the bottom. Brush the top with egg. Cut the pastry into rolls about 4 cm in length. Bake for 20 minutes, or until golden brown. Let cool, and serve.
