1. Preheat grill to 300° to 350° (medium) heat. Grate zest from lime to equal 1 tsp. Cut lime in half; squeeze juice from lime to equal 3 Tbsp.
2. Combine chicken, lime zest, lime juice, 1/4 cup olive oil, and next 3 ingredients. Let stand 10 minutes. Remove chicken from marinade, discarding marinade.
3. Grill chicken, covered with grill lid, 5 to 7 minutes on each side or until done.
4. Prepare pasta according to package directions. Combine vinegar, mustard, and remaining 1 Tbsp. olive oil. Toss orzo, bell pepper, cucumber, and dill with vinegar mixture. Season with salt and pepper to taste. Serve with grilled chicken.