Combine boiling water and sun-dried tomato sprinkles in a bowl, and let stand 30 minutes. Drain.
Preheat oven to 400°.
Lightly spoon flour into dry measuring cups, and level with a knife. Combine the flour and next 6 ingredients (flour through salt) in a bowl. Combine tomatoes, buttermilk, oil, and egg whites in a bowl. Add sun-dried tomato mixture to flour mixture, stirring just until moist (dough will be sticky).
Turn dough out onto a lightly floured surface, and knead lightly 4 times with floured hands. Pat dough into an 8-inch circle on a baking sheet coated with cooking spray. Cut dough into 12 wedges, cutting into, but not through, dough. Bake at 400° for 18 minutes or until golden.