Preheat oven to 350 degrees.
Wash, peel and dice three beets, stems removed. Add a drizzle of olive oil to a large skillet over medium heat. Sauté 1-2 minutes. Add 1\2 C. pomegranate juice (you may need slightly more depending on the size of your pan; you want the beets to be submerged about one quarter of the way.) Add a full sprig of tarragon and salt and pepper. Let come to a simmer and cover with aluminum foil. Place in oven for about 1 hour until fork tender. Check halfway through cooking to see if juice is evaporated and add more if necessary. By the end of cooking, the juice should be reduced to nearly dry. Taste. Season with salt and pepper as needed.
Remove beets from pan, and disgard tarragon. Toss beets with about 1/4 C. feta cheese and 2 T. pistachios.