Preheat oven to 350°F (175°C). Grease two 9-inch round cake pans, line bottoms with parchment paper, grease the parchment, and dust with flour.
In a medium bowl, whisk together cake flour, cocoa powder, baking soda, and salt for at least 30 seconds. Set aside.
In a large bowl, beat vegetable oil and granulated sugar on medium speed for 2 minutes. Add eggs one at a time, beating well after each addition and scraping down the bowl.
In a small bowl, stir together buttermilk, red food coloring, and vanilla. With mixer on low, alternate adding dry ingredients and buttermilk mixture to the oil mixture, beginning and ending with dry ingredients. Mix just until combined.
Add white vinegar and mix on low for 10-15 seconds. Give the batter a final stir with a rubber spatula. The batter should be smooth, pourable, and vibrant red.
Divide batter evenly between prepared pans. Tap pans gently on the counter to release air bubbles. Bake on the middle rack for 28-32 minutes, until a toothpick inserted in the center comes out with a few moist crumbs.
Cool cakes in pans on wire racks for exactly 10 minutes. Run a knife around edges, invert onto racks, peel off parchment, flip right-side up, and cool completely for at least 1 hour.
Beat softened cream cheese and butter on medium speed for 2-3 minutes until light and fluffy. Gradually add powdered sugar one cup at a time on low speed, then beat on medium for 2 minutes. Add vanilla and salt, beat 1 more minute until silky smooth.
Place one cake layer on a serving plate. Level the top if domed. Spread about 1 1/2 cups frosting over the first layer. Place second layer on top and press gently. Apply a thin crumb coat, refrigerate 15-20 minutes, then apply the remaining frosting in a thicker final coat. Decorate as desired.