TO PREPARE DRESSING Place orange juice, vinegar and tarragon in small, heavy saucepan over medium-high heat. Cook, watching carefully, until mixture is reduced to half, about 6 tablespoons.
Pour into bowl. Whisk in garlic, salt, pepper and oil until blended. Set aside.
TO PREPARE SALAD Melt butter in heavy medium-size saucepan over medium heat. Add rice; stir until all grains are coated well.
Add stock and bring to a boil. Reduce to a simmer and cook, covered, until tender, 30 to 40 minutes.
Remove from heat; let cool. Toss rice with dressing.
Add turkey, cranberries, pecans, green onions, grapes, 1 tablespoon fresh or 1 teaspoon dried tarragon and orange zest. Taste and season salad with salt, pepper and additional tarragon, if desired.
(Salad can be prepared 1 to 2 days ahead, covered and refrigerated. Bring to room temperature 30 minutes before serving.)
TO SERVE Arrange border of lettuce leaves on serving plate if you wish. Mound salad on top. Garnish with chopped tarragon and border of orange slices, if desired.
Note: Texmati rice, a long-grain American basmati rice, works well in this recipe. Cook it as you would the brown rice, 20 to 25 minutes, and then remove from heat and keep covered 10 minutes.