Preheat the oven to 350 degrees. Line 12 cupcake tins with liners. Set aside.
In a large bowl, sift together the flour, sugar, cocoa, baking soda, and salt. Add the vanilla, vinegar, melted butter, and warm water; stir until just combined.
Measure about 1/4 cup of batter into each cupcake liner. Bake for 18-20 minutes, or until a toothpick inserted into the center of a cupcake comes out clean.
Remove from the tin and cool on a rack before frosting.
Make the buttercream:
In a medium bowl, cream together the butter and strawberry preserves. Sift in 2 cups of the powdered sugar, then add the half & half and vanilla; beat until combined. Sift in the final cup of powdered sugar and beat until fluffy. Add more powdered sugar or half & half as needed to reach your desired consistency. Pipe onto cooled cupcakes.