In a large bowl, cream the vegetable shortening and two sugars. Beat in the eggs one at a time, beating well after each addition. Beat in the vanilla extract and lemon juice. Gradually blend in the dry ingredients. Fold in the macadamia nuts and the oats. Cover and chill for 4 hours.
Preheat oven to 325 degrees. Lightly grease 2 baking sheets.
Drop the dough by spoonfuls 1-2 inches apart onto the prepared baking sheets.
Bake for 15 to 18 minutes, untillightly colored. Cool.