Preheat oven to 400°.
Combine first 7 ingredients in a bowl; cut in margarine with a pastry blender or 2 knives until mixture resembles coarse meal. Add bell pepper and buttermilk; stir just until moist.
Pat dough into a 6-inch circle on a baking sheet coated with cooking spray, and cut into 4 wedges. Bake at 400° for 20 minutes or until golden. Serve warm.