01 - Preheat the oven to 425°F. Line a large baking sheet with parchment paper.
02 - Arrange the fennel and red onion wedges on the prepared baking sheet. Drizzle with 2 tablespoons olive oil, season generously with salt and pepper, and toss to coat evenly. Roast for 20 minutes until beginning to caramelize.
03 - Scatter the halved cherry tomatoes over the baking sheet and toss gently with the roasting vegetables. Continue roasting for 10 to 15 minutes until all vegetables are golden and tender.
04 - While the vegetables roast, bring 3 cups water and 1/2 teaspoon salt to a boil in a saucepan. Add the rinsed farro, reduce heat to a simmer, and cook uncovered for 20 to 25 minutes until tender yet still pleasantly chewy. Drain any remaining liquid.
05 - In a small bowl, whisk together the extra-virgin olive oil, lemon juice, red wine vinegar, Dijon mustard, minced garlic, salt, and black pepper until well emulsified.
06 - Transfer the drained farro to a large mixing bowl. Add the roasted vegetables and pour the dressing over the top. Toss thoroughly until everything is evenly coated.
07 - Let the salad rest for 5 minutes so the grains absorb the dressing. Gently fold in the chopped parsley, toasted pine nuts, and crumbled feta cheese if using.
08 - Serve warm or at room temperature as a side dish or light main course.