Sift together the first 5 ingredients (whole wheat flour through sea salt); set aside.
In a large bowl cream together the vegetable shortening and brown sugar; add the vanilla extract. Add flour mixture to shortening mixture, alternating with the milk. Mix well after each addition.
Divide dough into thirds; roll out each portion onto a cookie sheet to 5" x 15" X 1/2" thick. Cut into six 2-1/2" x 3" squares. Prick each cracker several times.