Preheat your oven to 350°F (175°C).
In a blender, combine the washed strawberries, sugar, oil, eggs, vanilla extract, and orange zest if using. Blend until smooth.
Gradually sift the flour and baking powder into the blender. Use a spatula to gently fold the dry ingredients in, mixing just until incorporated. Avoid over-blending to keep the cake light.
Line a 7-inch round cake pan with parchment paper.
Pour the batter into the prepared pan and smooth the top.
Bake for about 45 minutes or until a toothpick inserted in the center comes out clean.
Let the cake cool in the pan for 10 minutes.
Carefully transfer to a wire rack or plate to cool completely.
Once cool, dust with icing sugar or decorate with your favorite icing.