Pre-heat the oven to 350ºF.
Grease and line the bottom of 3 8-inch cake pans with a circle of parchment paper. Grease the parchment and the sides of the pan as well.
In a small bowl, mix together the flour, baking powder, baking soda, and salt. Whisk to combine. Set aside.
Use an electric mixer to beat the butter at medium speed for 30 seconds. You can use a stand mixer or a hand mixer.
Add the granulated sugar, the oil, and beat together with the butter for another 1 to 2 minutes, until the mixture is light and fluffy.
Scrape the bowl every so often to ensure everything is getting nicely incorporated together.
Add the eggs, one at a time, mixing until incorporated before adding the next egg.
Add the vanilla and mix to combine.
Pour the sour cream, and 1/2 cup of the strawberry puree in the bowl and mix. You can place the remaining strawberry puree in the fridge, covered, to use in the frosting later.
At this point, you can add a couple of drops of pink food coloring to the cake if desired.
Add half of the buttermilk to the bowl and mix on low.
Add half of the dry ingredient mixture and stir to combine
Add the remaining buttermilk and mix.
Finish by adding the last half of the dry ingredients. Stir to combine.
You can also use the spatula instead of the mixer to fold the batter during this final stage. Avoid over mixing, to prevent the cake from turning out dry.
Divide the batter evenly between the 3 pans.