To make the pickle liquid, combine water, vinegar, and sugar in a bowl and whisk until the sugar has dissolved.
Divide the pickle juice into twp bowls. Add carrots and daikon separately in each bowl. Let the vegetables pickle for 2 hours.
Fill a large pan with ½ cup of water and bring to a boil over medium high heat.
Add the clams to the pan, cover with a lid, and cook for 2-3 minutes, or until the clams have fully opened.
Remove the clams and plunge them into a bowl filled with iced water to prevent further cooking.
Drain the clams and pull them from the shell. Trim off the rounded foot at the base of the clam and cut out the black stomach, which will contain sand and grit. Cut the clams in half and set them aside until you're ready to assemble the salad.
To make dressing, combine everything in a bowl and whisk together until combined. Set aside until ready to serve.
When ready to assemble salad, drain carrot and daikon.
In a large bowl, combine razor clams, carrots, daikon, and herbs. Pour half of the dressing over salad and toss to combine.
Transfer to a salad platter and garnish with peanuts and fried shallots. Serve with reserved dressing and prawn crackers.