In a large bowl, combine the flour, sugar, cream of tartar, baking soda and salt. In another bowl, combine eggs, yogurt and sour cream; stir into dry ingredients just until moistened. Fold in strawberries. Fill greased or paper-lined muffin cups two-thirds full.
For topping, combine the brown sugar, flour and cinnamon in a bowl; cut in butter until mixture resembles coarse crumbs. Sprinkle over batter.
Bake at 350° for 30-35 minutes or until a toothpick comes out clean. Cool for 5 minutes before removing from pan to a wire rack.