Here is a video of RYA Coach Assessor Elsa Chance slowing down and stopping her Oppie in one of the Helford River Children's Sailing Trust's videos. The sequence for the helm slowing down and stopping a Mirror is identical.
To get going again in a Mirror, ask your crew to pull the jib in (rather than pull the mainsail in). This will help push the bow of the boat away from the wind so it bears away onto a reach.
