Method:
For the salad, put bulgur wheat, boiling water, lemon juice and oil into a large bowl and stir gently. Immediately cover with a dish towel and set aside for 1 hour. Uncover and fluff with a fork. Add zest, parsley, chives, onions, mint, salt and pepper and toss gently to combine. Cover with plastic wrap and chill for at least 1 hour.
Meanwhile, for the salmon, whisk together 2 tablespoons of the oil, zest and juice, salt and pepper in a wide, shallow dish. Arrange salmon in dish, turn to coat all over with marinade, cover and chill for 30 minutes.
Preheat grill and brush grates with oil. Remove salmon from marinade; discard remaining marinade. Arrange salmon on grill, skin side up, and cook, flipping once, until golden brown on both sides and just cooked through, about 10 minutes total. Transfer to a platter and set aside to let rest for 5 minutes.
Stir together onions, tomatoes, cucumbers, remaining 1 tablespoon oil, lemon juice, salt and pepper in a medium bowl. Serve salmon on a bed of tabbouleh salad with the tomato-cucumber mixture spooned over the top.