Add strawberry puree to a small saucepan. Cook over medium heat until puree is reduced by half or until about one and a half cups.

Meanwhile, preheat oven to 350 degrees Fahrenheit.

Grease a 9×13-inch baking pan (you can also use two round 9-inch or 8-inch pans. Bake times will vary). Combine oil, milk, vinegar, eggs, vanilla, sugar, and flour. Swirl in reduced strawberry puree (mix it in somewhat, but you don’t have to mix it in completely). Bake for 15 minutes. (Since the batter is liquidy, we want the cake to set somewhat before adding the streusel on top so it doesn’t sink in.)

Meanwhile, prepare the streusel. Crush freeze-dried strawberries to a powder-like consistency while the package is still closed (this is easy to do with your hand). In a bowl, combine flour, sugar, and strawberry powder. Mix in margarine until mixture is moist and not powdery. Sprinkle on top of cake and bake an additional 10-15 minutes.