Cook the beef.
In a large skillet over medium heat, cook the ground beef, breaking it apart, until fully browned. Drain excess fat if needed.
Finish the filling.
Add the diced potatoes, salt, black pepper, allspice, and seasoning salt. Stir well, cover, and cook over medium-low heat, stirring occasionally, until the potatoes are tender. If the pan becomes dry before the potatoes soften, add a small splash of water.
Stir in the chopped cilantro. Remove from the heat and let the filling cool completely before wrapping. Any excess moisture should evaporate or be drained away.
Make the sealing paste.
In a small bowl, mix the flour or cornstarch with the water until smooth. The paste should be thick enough to brush along the wrapper edges without running.
Fill and fold.
Keep the wrappers covered with a lightly damp kitchen towel while you work. If using large square spring roll wrappers, cut them into wide strips suitable for folding.
Fold one end of a wrapper strip diagonally, then fold again to form a triangular pocket. Hold the pocket open and spoon in a small amount of the cooled beef and potato filling.
Continue folding the filled pocket along the strip, maintaining the triangle shape. Tuck in any small corners, brush the final edge with sealing paste, and press firmly to close. Make sure the corners are sealed so the filling stays inside.
Fry until golden.
Heat about 2 inches of oil in a deep, heavy pot to 350°F.
Carefully add the sambosa in small batches. Fry for approximately 1–1 1/2 minutes per side, or until golden brown and crispy.
Remove with a slotted spoon and transfer to a wire rack or a plate lined with paper towels to drain.
Serve.
Serve warm while the wrappers are crisp and the filling is hot.