In a large mixing bowl, add in the flour, sugar and baking powder. Mix in the raisins.
Create a hole in the middle of the bowl, pushing the dry ingredients to the sides. Pour the sour cream into the hole and crumble the margarine in with your fingers as well. Mix everything together with a big spoon until the dry ingredients absorb all of the sour cream and margarine. Continue to knead the dough with your fingers until the consistency is uniform.
Sprinkle a small amount of flour on top of a cast-iron baking sheet. Take half of the dough mixture out of the bowl and place it in a circular mound on top of the baking sheet. Cut the dough with a knife into 8 pieces by making a plus sign, and then a multiply sign. Make sure to separate all 8 wedges of dough to allow room for each piece to expand in the oven without touching. Bake until very lightly browned, 10 to 15 minutes. Repeat this process with the second half of the dough.