Wash the berries.  Soak in fruit wash or water + ACV.

Separate any pits, stems, or other parts you don't want from them and place them on a cookie sheet.

Fill the cookie sheet until it's full, in a single layer, then transfer to the freezer for 2 - 3 hours or until frozen.

Scoop the frozen berries into a large plastic freezer bag (yes, it's okay to use plastic here.  Heat and fat make the chemicals leach, but we're not dealing with either).  Transfer to a freezer.  If you don't want to use plastic bags, mason jars will also work -- they just won't hold as much and will break if they fall out.