This recipe is great for decorative frosting, such as lettering or piping!
In a bowl or measuring cup, combine the shortening and butter. Mix well with a spoon or fork.
Add the vanilla, and mix well.
Slowly add the powdered sugar until it reaches the consistency you need. It may take a minute to fully mix in, just keep stirring! =)
(Note: I found it helpful while stirring to kind of smoosh the mixture against the wall of the measuring cup (or bowl), and then mix it all together; repeat as needed.)
Add the food coloring, if desired.
If you don't have a cake decorating bag, you can just put it all in a small Ziploc plastic baggie, cut a *tiny* bit of the corner off and use that.