Place sirloin steak on a flat work surface. Slice horizontally through the middle with a very sharp knife, being careful not to cut all the way through to the other side. Open the 2 sides and spread them out like an open book. Place in a dish, season with soy sauce and lemon, and let marinate briefly.
Mix ground pork, sweet relish, salt, and pepper together in a bowl.
Remove the steak from the lemon-soya sauce marinade and lay it on a flat surface, e.g. a cutting board. Reserve the marinade. Spread ground pork mixture over the steak. Arrange chorizo, eggs, carrot, and ham over the pork. Roll steak into a log until filling is entirely covered; secure at both ends with toothpicks. Tie the meat roll with a string.
Heat oil in a large pot over medium heat. Add the meat roll; cook until all sides are browned, about 10 minutes. Add water, tomatoes, onion, garlic, peppercorns, bay leaves, and the reserved marinade. Cover and cook for 5 minutes. Add tomato sauce, salt, and pepper. Reduce heat to low and simmer until sauce flavors blend and meat roll is hot in the center, about 20 minutes.
Remove meat roll from the sauce; place on a flat work surface and cut crosswise into slices. Arrange slices on a platter. Pour sauce on top.