Thaw dough until firm, yet easy to roll. Roll out each dough in package to a large rectangle.

Sauté onions in a bit of oil; shut off flame. Add sauerkraut, mayonnaise, mustard, and pastrami; mix well. Divide mixture in half.

Spread each portion of mixture onto one dough rectangle and roll up jelly roll style. (You can also mound mixture in a line down the center of dough and close up, knish style.)

Place, seam-side down, on cookie sheet and brush with beaten egg. Bake at 350 degrees Fahrenheit for one hour. Let cool slightly before cutting.