For the Pickled Red Onions, mix vinegar, sugar and salt in tall jar or plastic storage container. Add onions, making sure all pieces are submerged in liquid. Cover. Let stand at room temperature at least 30 minutes or until ready to serve.
For the Hummus, drain chickpeas, reserving 1/2 cup of the liquid. Place chickpeas, tahini, lemon juice, Seasoning, salt and red pepper in food processor; cover. Process until smooth, scraping down sides as necessary. Add reserved liquid; process until smooth. Cover and set aside.
For the Shawarma Steak, mix vinegar, oil, 3 teaspoons of the Shawarma Seasoning and garlic in small bowl. Reserve 2 tablespoons marinade; set aside. Place steak in a large resealable plastic bag or glass dish. Add remaining marinade; turn to coat well. Refrigerate 30 minutes or longer for extra flavor.
Remove steak from marinade. Discard any remaining marinade. Sprinkle steak evenly with remaining 2 teaspoons Seasoning.
Grill steak over medium-high heat 6 to 8 minutes per side or until desired doneness, brushing with reserved marinade during last few minutes of grilling. Let stand 5 minutes. Slice into thin strips.
To serve, divide hummus among 4 bowls. Top with steak and pickled red onions. Drizzle with additional olive oil and sprinkle with parsley to serve, if desired.