Preheat oven to 350F and grease a one 9-inch round pan.

In a mixer, beat shortening and 3/4 cup sugar until light and fluffy. Add egg and beat well.

Make a paste of cocoa and red food coloring; add to creamed mixture.

Mix buttermilk, salt, and 1 tsp vanilla.

Add the flour to the batter, alternating with the buttermilk mixture, mixing just until incorporated.

Mix soda and vinegar and gently fold into cake batter. Don't beat or stir the batter after this point.

Pour the batter into a prepared pan.

Bake in preheated oven for about 30 minutes - bake until a tester inserted into the cake comes out clean

Put cakes on a wire rack until completely cool.

Spread chocolate frosting all around the cake.