Heat grill or grill pan to medium-high heat. Grill pitas on medium-high heat for 1 to 2 minutes per side, until lightly charred. Set aside to cool.
In a large bowl, whisk together olive oil, lemon juice, zest, vinegar, garlic, 1/4 tsp of the salt and the pepper. Toss dressing with romaine, tomatoes, cucumber, scallions, parsley, mint and remaining 1/2 tsp salt. Tear cooled pita into bite-size pieces and toss with rest of salad.