Strip dill from the larger stems and place in a food processor. Pulse until minced.

Cut feta in chunks, and add to the processor. Process until finely chopped.

Add yogurt, 1-2 T at a time, and process for a minute in between additions. Check the texture - you may need anything from 3 to 5 T altogether, depending on the moisture of your cheese and your preferences. When you think you have the right amount, whip for another minute or so until light and fluffy.

Serve at once, or cover and refrigerate for later.