1. Place broth in bowl. Heat at 210°F for 4 minutes or until simmering. Add fish. Cook at 190°F for 8 minutes or until fish flakes easily with a fork. Remove from broth and cover to keep warm. Discard broth.
2. Place the spinach/arugula blend, parsley, tarragon, sage and mint in the bowl fitted with the ultrablade knife. Pulse for 30 seconds, scraping down the sides of the bowl every 10 seconds. Replace the ultrablade knife with the mixer and scrape down the sides of the bowl.
3. Add the butter and launch the P1 simmer program at 270°F for 5 minutes.
4. At the end of the program, add the sour cream, lemon juice, salt and pepper. Launch at speed 6 at 110°F for 45 seconds.