Preheat your oven to 180°C (350°F). Grease a 23cm round cake pan and line the bottom with parchment paper, then set aside.
Sift together the flour, sugar, baking soda, and salt in a large bowl until well combined. This aerates the dry ingredients and removes lumps, ensuring a smooth batter.
In a separate bowl, whisk together the oil, buttermilk, eggs, and vinegar until smooth and slightly frothy. The mixture should look uniform and slightly glossy.
Add a few drops of red food coloring to the wet mixture, aiming for a deep, blood-red hue. Mix thoroughly until the color is evenly distributed and vibrant.
Pour the wet mixture into the dry ingredients. Gently fold them together with a spatula or spoon until just combined. The batter should be smooth, slightly bubbly, and pourable without lumps.
Pour the batter into your prepared cake pan, smoothing the top with a spatula for an even surface. Tap the pan lightly on the counter to release any air bubbles.
Bake in the preheated oven for 30-35 minutes, until the edges are golden and the top cracks lightly. Insert a toothpick into the center; it should come out clean.
Remove the cake from the oven and let it cool in the pan for about 10 minutes until slightly firm and easier to handle.
Turn the cake out onto a wire rack and peel away the parchment paper. Cool completely until the cake feels firm to touch and no warmth remains.
Once cooled, slice to reveal the vibrant blood-red crumb. Serve as is or with your favorite frosting for a dramatic presentation.
