Cook the farro according to package instructions, usually about 25-30 minutes, until tender. Drain and set aside to cool.
Preheat the grill to medium-high heat.
Toss the asparagus with 1 tablespoon of olive oil, 1/2 teaspoon of salt, and black pepper.
Grill the asparagus for about 5-7 minutes, turning occasionally, until tender and slightly charred. Remove from the grill and let cool slightly.
In a large bowl, combine the cooked farro, grilled asparagus, lemon juice, lemon zest, thyme, and remaining olive oil. Toss gently to combine.
Adjust seasoning with the remaining salt if needed.
Serve the salad warm or at room temperature, topped with grated Parmesan cheese and toasted walnuts if desired.