To make the dressing, in a bowl, mix the fish sauce, lime juice, and palm sugar until dissolved, then add the garlic and chili and mix well.
To cook the seafood, in a pot over high heat, bring water to a boil, add the squid and shrimp, and cook for about 1 minute until just cooked through, then drain immediately.
To cook the pork, in the same pot over high heat, add the ground pork with the fish sauce and cook for about 3 minutes until fully cooked, then drain.
To assemble the salad, in a large bowl, combine the onion, tomatoes, cooked shrimp, squid, and pork, then pour in the dressing and toss gently until evenly coated.
To finish, add the Chinese celery and cilantro, toss again, and serve immediately.