In a medium pot, bring ¾ cup (180 ml) of the coconut milk to a boil over medium high heat. Add the curry paste and mix well, then turn the heat down to medium. Keep stirring until the mixture is very thick, and the coconut oil separates from the paste.
Add the remaining coconut milk and stir to mix. Then add the chicken, 1 tablespoon of fish sauce, 1 tablespoon palm sugar, 1 tablespoon of tamarind, and just enough water to keep the chicken barely submerged. Bring to a simmer, and let the chicken simmer gently for 30 minutes.
Meanwhile, pierce the cherry tomatoes with the tip of a parting knife, making about a half-inch incision.
Once the chicken is done, add the potatoes and onion and simmer for another 15 minutes or until chicken is fork tender and the potatoes are fully cooked. Top it up with more water as needed to keep the potatoes barely submerged.
Taste and adjust seasoning with the remaining fish sauce, sugar and tamarind as needed. Turn off the heat and immediately stir in the pierced cherry tomatoes and let the residual heat of the curry gently cook the tomatoes for a few minutes before serving.
Sprinkle with fried shallots, if desired. Serve with jasmine rice.
