How to play upper strings to sound like strumming while keeping bass note?
E|----6-- B|---6--- G|--6---- D|------- A|------- E|--6----
Like quick strumming, there should be almost no delay between notes.
Pluck the bass note with your thumb. Strum the remaining notes with back of the nails of your 1st, 2nd or 3rd finger.
As an alternative to Slim's technique, strum all strings but mute the A and D strings with the fretting hand. It is possible to mute these two strings for any particular fingering for the minor 7 voicing in question.