01 - Rinse farro under cold water. Bring 3 cups water and 1/2 teaspoon salt to a boil in a medium saucepan. Add farro, reduce heat, and simmer uncovered for 20–25 minutes until tender but still chewy. Drain and spread on a tray to cool.
02 - Preheat grill or grill pan over medium-high heat. Lightly brush peach halves with olive oil. Grill cut side down for 2–3 minutes per side until grill marks appear and peaches are softened. Let cool slightly, then cut into wedges.
03 - Whisk together olive oil, balsamic vinegar, honey, Dijon mustard, minced garlic, salt, and pepper in a large bowl until emulsified.
04 - Add cooled farro, grilled peach wedges, cherry tomatoes, red onion, and arugula to the bowl with dressing. Toss gently to coat evenly.
05 - Fold in most of the basil leaves, reserving a few for garnish. Taste and adjust seasoning with salt and pepper as needed.
06 - Transfer salad to a serving platter. Sprinkle with crumbled feta cheese and toasted pine nuts if using. Garnish with remaining basil. Serve immediately or at room temperature.