Preheat oven to 350 degrees F. Lightly grease large cookie sheet.
In a small bowl, beat together egg whites, oil, coffee, and vanilla.
In a large bowl, stir together flour and remaining ingredients until well mixed. Pour egg mixture onto dry ingredients and stir until combined. Shape mixture into two 12" by 1" logs; place both on cookie sheet and flatten slightly. Bake 30 minutes. Remove from oven and cool 10 minutes.
Transfer one log to cutting board. Slice diagonally into scant 1/2-inch-thick biscotti. Arrange biscotti, cut side up, on cookie sheet. Repeat with remaining log, using a second cookie sheet if necessary.
Bake 20 minutes. Transfer to wire rack to cool. Store in an airtight jar up to 1 month.