MAKE-AHEAD NOTE: Bulgur can be made up to 3 days ahead. Refrigerate in a covered container until ready to mix with the rest of the ingredients.
Add the water and bulgur to a medium saucepan and bring to a boil, uncovered, over medium heat. Reduce the heat to low, cover, and cook until the bulgur has absorbed all the water, about 12-15 minutes. Remove from the heat, fluff with a fork, and cool to room temperature.
Rinse the parsley and chop off any thick, woody stems and yellowing leaves. Pulse the parsley and mint leaves in a food processor until minced. Stir the herbs, cucumber, tomatoes and scallions with the bulgur in a large bowl. Whisk the lemon juice, oil, and salt together and stir into the tabbouleh. Taste and add more salt if desired. Serve immediately or refrigerate overnight in a covered container. Serve cold or at room temperature.