Preheat grill. Rub beets with 2 tablespoons of the olive oil and wrap separately in aluminum foil. Place on the grill over medium heat and let cook for 1 hour or until tender. Remove from foil and let cool slightly. Peel and cut into 1-inch pieces. Whisk together the olive oil, lemon juice and tarragon and season with salt and pepper.
Arrange the arugula on a platter, top with beets and goat cheese and drizzle with lemon vinaigrette. Sprinkle with pine nuts.