Grate or julienne the green papaya and place in a shallow bowl. Add 1 tablespoon of salt and let it sit for 1-2 hours until papaya begins to release liquid. Use a cheesecloth to squeeze out the juices and salt. Set aside.
To make the pickling solution, combine vinegar, sugar, water, and remaining salt in a small saucepan over medium heat. Bring to a simmer and stir occasionally until sugar is dissolved. Add in the shallots/ red onion, ginger, garlic, and peppercorn and cook for another 2-3 minutes.
In a deep bowl, combine the papaya, carrots, red pepper, and raisins. Pour the pickling solution and gently mix the vegetables.
Transfer atchara to sterilized jars with tight-fitting lids. Refrigerate for 1-2 days to allow the flavors to develop.