Make the dressing: In a small bowl, whisk lime juice, zest, olive oil, salt, hing, and pepper (plus chili flakes if using).
2 Assemble salad: In a mixing bowl, gently combine avocado, tomatoes, celery, and cilantro.
3 Toss & serve: Drizzle dressing over the salad and gently toss. Serve immediately.
Note: To prep ahead, mix everything except the avocado and dressing. Add both just before serving to prevent browning and sogginess.