In a small bowl, toss together the halved tomatoes with lemon juice, olive oil, za'atar and season with salt and pepper to taste; set aside.
To assemble, fill each bowl with two cups of romaine and a half cup of cooked grains (if using.) Top with one serving each of the chicken and cucumber Laban. Finally, top with two tablespoons of hummus and 1/4 cup of the tomato mixture. Serve with extra lemons for squeezing before eating!
Nutrition facts do not include cooked grain as calories vary based on grain.