Thin breadsticks are enriched with a lively flavor and hue when they're infused with extracts of beet, carrot, parsley, or tomato.
Preheat oven to 350 degrees. Pulse flour, 1/4 teaspoon salt, and the baking powder in a food processor. Add shortening; pulse until mixture resembles coarse meal. With processor running, gradually add 1/2 cup ice water; process until a dough forms, about 1 minute. (For flavored breadsticks, substitute one of the juice mixtures for the 1/2 cup ice water.) If dough is dry, add up to 1/4 cup more ice water, 1 tablespoon at a time, pulsing after each addition.
On a lightly floured surface, pat dough into a rectangle; roll out to an 8-by-10-inch sheet (1/4 inch thick). Cut lengthwise into 1/4-inch-wide strips.
Roll each strip with your hands to 16-inch-long log; cut in half. Arrange 1/2 inch apart on baking sheets. Brush with oil; sprinkle with remaining 1/2 cup salt.
Bake until firm, 12 to 14 minutes; let cool on a wire rack. Store in airtight containers at room temperature up to 4 days.