Preheat oven to 350 degrees. Grease and flour a 13 x 9 pan.
Stir together flour, baking powder, salt and sugar in a mixing bowl. Set aside.
Melt butter in a saucepan, then add oil and water. Bring to a boil for 1 minute.
Pour wet ingredients into dry ingredients in mixing bowl. Blend with a mixer on medium speed for 1 minute.
In a separate bowl, whisk eggs and buttermilk together. Pour into contents in mixing bowl.
Add mashed strawberries and mix batter for 1 minute on medium speed until combined
Pour batter into the pan.
Bake for 40 minutes until cake springs bake in the center (or a toothpick inserted in the center comes out clean).
Remove from oven and allow to cool for 5 minutes before transferring to a wire rack.