Preheat oven to 350°.
Lightly spoon 3 cups flour into dry measuring cups; level with a knife. Place 3 cups flour, 2 tablespoons sugar, baking powder, and salt in a food processor; pulse 2 to 3 times or until combined. Add butter; pulse 10 times or until mixture resembles coarse meal. Add buttermilk, rind, and lemon juice; pulse until just combined. Scrape dough onto a lightly floured surface with a rubber spatula; sprinkle with 1 teaspoon flour (dough will be soft).
With floured hands, pat dough into a 4-inch circle; place on a baking sheet lined with parchment paper. Pat dough into an 8-inch circle. Cut dough into 10 wedges, cutting into but not through dough. Brush egg white over dough; sprinkle with 1 teaspoon sugar. Bake at 350° for 25 minutes or until golden. Cool on a wire rack. Serve with Quick Blackberry Jam.
Note: Nutritional analysis includes Quick Blackberry Jam.