Preheat oven to 375°F. Line cookie sheet with parchment paper. In a medium bowl, beat eggs lightly with a fork, stir in sugar, oil, and vanilla. Set aside.
In a large bowl, stir together whole-wheat flour, oats, barley flour, oat bran, wheat bran, dry milk powder, baking powder, orange zest, 1 Tbsp orange zest and baking soda.
Add egg mixture to flour mixture; stir with a wooden spoon until combined. Stir in chocolate pieces, walnuts, and, if desired, coconut.
Drop dough by rounded teaspoons 2 inches apart onto prepared cookie sheet. Bake for 8 to 10 minutes or until edges are set and bottoms are lightly browned. Transfer cookies to a wire rack; let cool, garnish with orange zest.