18.7Dorian over a minor 7 chord

Dm7:

D F A C

D Dorian adds:

E = 9

G = 11

B = 13

So:

D E F G A B C

works beautifully over Dm7 when Dm7 functions as ii in C major.

Try emphasizing B.

That's the Dorian 6/13.

It gives the minor chord a brighter, more open sound than natural minor.