Preheat oven to 425 degrees F (220 degrees C). Lightly grease a baking sheet with 1 teaspoon margarine.
Sift all-purpose flour, whole wheat flour, baking soda, cream of tartar, and salt together into a bowl; mix well. Add 2 tablespoons margarine and rub into flour mixture until crumbly. Pour milk over mixture and stir to form a soft, but not sticky dough.
Dust your hands with flour and bring dough together, shaping into a ball. Place ball onto the baking sheet and flatten slightly. Cut an "x" on the top to divide it into quarters.
Bake in the preheated oven until golden and risen, 20 to 25 minutes. The base should sound hollow when the loaf is lifted using a towel and you knock on it with your knuckles. Cool a wire rack.