In a pot add the strawberries, sugar, vanilla extract, and lemon zest. Cook over low to medium heat, once the mixture starts to get hot and a slight boil use a potato masher to mash the strawberries down.
Once the cake is baked use the handle of a wooden spoon to poke lots of holes in the cake. Then pour the strawberry sauce on top and use an offset spatula to help push it down into the holes.