two 12-cup muffin tins; a piping bag fitted with a star tip
For the cupcakes: Preheat the oven to 350 degrees F. Line two 12-cup muffin tins with paper liners.
Whisk together the flour, sugar, cocoa powder, baking powder, baking soda and salt in a large bowl. In another bowl, whisk together 1 cup water and the oil, eggs and vanilla until well blended. Pour the egg mixture into the flour mixture and stir until just incorporated.
Divide the batter evenly between the prepared muffin cups. Bake until a wooden pick inserted into the center of the cupcakes comes out clean, 18 to 20 minutes. Cool the cupcakes in the tins for 5 minutes, then remove from the tins and cool completely on a wire cooling rack.
For the frosting: In the bowl of stand mixer fitted with the paddle attachment, beat the butter until soft and fluffy. Gradually add the confectioners' sugar, beating until smooth. Beat in the vanilla. Add 1 tablespoon water; beat to the desired consistency. Remove half of the frosting to a bowl. To the remaining half, add the red food coloring and strawberry preserves; beat until incorporated.
Fit a piping bag with a star tip. Set the bag, tip-side down, in a large cup and fill with both frostings, keeping each color separate in one half of the bag. Pipe the frosting onto the cupcakes.