How to Make It
Heat oven to 425° F. Toss the sweet potatoes, cumin, 2 tablespoons of the oil, and 1/2 teaspoon each salt and pepper on a large rimmed baking sheet. Roast until tender, 14 to 16 minutes. Let cool slightly.
Meanwhile, cook the bulgur according to the package directions. Let cool slightly. Whisk together the vinegar, the remaining 3 tablespoons of oil, and 1/4 teaspoon each salt and pepper in a small bowl.
Serve the sweet potatoes, bulgur, watercress, Feta, pistachios, and onion drizzled with the dressing.