In a large bowl, cream margarine and sugar. Add whites one at a time and mix carefully (don't over mix). Stir in sour cream and set bowl aside.
In a medium bowl mix dry ingredients. Add in thirds to the margarine mix (batter will be stiff).
Stir in vanilla, zest and strawberries.
Lightly grease a 9 x 13 inch GLASS baking dish and spread batter in (it will spread thin, I got it even using an icing knife). Mix topping ingredients together until crumbly and sprinkle on top of better. Bake 20 minutes.
*Note: after baking, cover cake to prevent drying out.