Fry ground beef and onion together in skillet. Set aside.

Dissolve yeast in water. Add milk, sugar, butter, egg, salt and 2 cups of flour. Beat until smooth.

Add the remaining flour and knead until smooth and elastic. Form into 16 balls. (Dough will be very soft.)

On a floured surface, roll out each ball into a 5-inch circle.

Put 1/4 c. ground beef, 1 T. shredded cheddar cheese, and a squirt of ketchup and Dijon mustard in center of circle.

Pinch dough shut and place seam side down on a greased baking sheet.

Bake at 400 degrees F. for 12 minutes.