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 ½" thick. Cut into six 2-½" x 3" squares. Prick each cracker several times.
Bake at 350°F for about 12 minutes.