1. Preheat oven to 400°. In oven-safe pan, rub pork with 1/4 tsp rosemary and 1/2 tsp oil. Roast until thermometer in thickest part of pork registers 145° (25-30 minutes).
2. Meanwhile, cook rice in boiling lightly salted water until just tender (30 minutes); drain.
3. In a large bowl whisk remaining 2 TBSP plus 1 tsp oil with lemon zest and juice, mustard, and 1/2 tsp salt; remove 2 TBSP. Add rice, grapes, apple, and remaining 1/4 tsp rosemary to bowl; toss.
4. Serve pork thinly sliced with rice mixture and, if desired, green beans; drizzle with reserved vinaigrette.