Bring a large pot of water to the boil, add razor clams and cook for 1 minute. Remove the clams and submerge them in an ice bath to stop the clams from cooking and retaining its texture.
Remove the clams from its shell then place in a large mixing bowl discarding the shells. Add pickled vegetables, onion, perilla leaves, mint leaves, Vietnamese mint leaves, coriander, basil, fried shallots, fried garlic chips, garlic oil, and dipping fish sauce. Mix well, transfer to a plate and garnish with crushed peanuts and sliced chile.
To make the dipping fish sauce: Combine the fish sauce, vinegar, sugar, and water in a saucepan and place on medium heat. Stir well and cook until just before boiling point is reached, then allow to cool. To serve, finely chop the garlic and chile and stir through with the lime juice.