Preheat the oven to 350F and grease and flour your 10 cup bundt pan and set aside.
In a medium bowl, mix the flour, corn starch, cocoa powder, granulated sugar, baking soda, and salt to combine. Set aside.
In a different bowl, whisk the oil, melted butter, buttermilk, vinegar, eggs, vanilla extract, sour cream, and red gel food coloring until fully combined.
Sift in the dry ingredients in the wet mixture and whisk just until combined. Make sure to not overmix the batter.
Pour the red velvet cake batter into the prepared bundt cake pan, spread the batter evenly, and bake on the middle rack in the oven for 45-50 minutes or until a wooden skewer inserted in the center comes out clean.
Let the bundt cake cool down for 10 minutes before inverting it on a cooling rack to cool down fully.