Place the avocado, yogurt, lemon juice, olive oil, tarragon, garlic, salt and a few turns of pepper in a food processor and process very well until smooth. Set aside. Preheat the grill to high and lightly oil the grate. Combine the olive oil and honey and brush on both sides of the salmon. Sprinkle with salt and pepper. Place the salmon on the prepared grill and cook until easily flaked with a fork, 4 to 5 minutes per side. Top with a dollop of avocado sauce.
