Put berries in the ice cube tray, filling just to the top.
Pour water over the berries, covering them and filling the tray.
Put in the freezer to freeze overnight.
Keep in the freezer until ready to use.
Notes
I use mixed berries for my fruit cubes. Any berries will do though. Other frozen fruit can be used but the sizes are a little too big for making an ice cube, so you would have to chop them up. You can use any style of ice cube tray as well. For everyday use, I use the basic ice cube trays, but if I'm entertaining, I use the fun shapes like my heart tray.