Prepare the Tofu: Pat the pressed tofu block completely dry. Crumble it with your hands into a medium bowl, creating varied, feta-like shapes. Drizzle the lemon juice over the tofu, then sprinkle with the dried oregano and sea salt. Gently toss to combine and set aside to marinate.
Make the Vinaigrette: In a small bowl or a glass jar, combine the extra virgin olive oil, fresh lime juice, ground sumac, lime zest, and minced garlic. Whisk vigorously or shake the sealed jar until the dressing is well combined.
Build the Salad: On a large serving platter, arrange the cubed watermelon, chickpeas, diced cucumber, and sliced red onion to create the base of the salad.
Layer and Dress: Drizzle about half of the vinaigrette over the salad foundation. Evenly scatter the diced avocado and the marinated herbed tofu crumbles over the top. Sprinkle with the torn fresh herbs and the sliced jalapeño, if using.
Serve: Just before serving, drizzle the remaining vinaigrette over the entire salad. Serve immediately to enjoy the best texture and temperature.