In a medium bowl, mix together the ground beef, onion, salt and pepper until well blended. Set aside.
In a large bowl, stir together the flour and salt.
Pour in the eggs and milk, and stir until well blended using a sturdy spoon. Form the dough into 2 inch balls, and roll out into circles 1/4 inch thick on a floured surface.
Form the beef into golf ball sized balls, and place each one onto one half of a dough circle. Fold the other halves of the circles over to enclose the dough. Seal the edges using a saucer or pressing with your fingers.
Heat the oil in a deep fryer to 365 degrees F (185 degrees C), or over medium-high heat in a large deep skillet. Fry the Keuchle until golden brown, turning once. It should take about 10 minutes total for each batch.
