Preheat your grill to medium-high. Brush the chicken with 1 Tbsp. of the oil and then season with salt and pepper. Grill the chicken for 3 to 4 minutes per side, or until cooked through. Set the chicken on a plate and cool to room temperature. Thinly slice the chicken and store in the fridge until needed. Place the remaining oil and the mustard, tarragon, honey, lemon and orange juice in a small bowl and whisk to combine. Season the dressing with salt and pepper. Divide and mound the lettuce on two chilled dinner plates. Arrange the chicken, grapes and pecans on top of the lettuce. Drizzle with the dressing and serve.