01 - Preheat oven to 425°F (220°C).
02 - Toss sliced delicata squash with 1 tablespoon olive oil, 1/4 teaspoon salt, and 1/4 teaspoon pepper. Spread on a parchment-lined baking sheet and roast for 20-25 minutes, flipping halfway, until golden and tender.
03 - While squash roasts, rinse farro under cold water. Combine farro, 2 cups water, and 1/2 teaspoon salt in a medium saucepan. Bring to a boil, reduce to simmer, cover, and cook for 20-25 minutes until farro is tender but chewy. Drain any excess water and let cool slightly.
04 - In a small bowl, whisk together olive oil, lemon juice, Dijon mustard, honey, salt, and pepper for the dressing.
05 - In a large bowl, combine cooked farro, roasted delicata squash, arugula, and red onion. Drizzle with dressing and toss gently to coat.
06 - Top with pumpkin seeds and crumbled feta, if using. Serve warm or at room temperature.