Rinse the pork tenderloin and cut it into bite-sized pieces. Set aside in a bowl.

Peel the potatoes, rinse them, and cut into bite-sized pieces. Set aside.

Heat a skillet over medium heat and dry-roast the peanuts until golden brown and fragrant.

Mix the tamarind paste with water in a small bowl and set aside.

Heat a pot or deep pan over medium heat. When hot, add the thick part of the coconut milk and bring to a boil.

Once the coconut milk is boiling, add the Massaman curry paste and cook until the oil separates.

Add the pork pieces and stir to coat with the curry paste. Pour in the remaining coconut milk and simmer until the pork is tender.

Add the potatoes and cook until just tender but not falling apart. If the liquid reduces too much, add more coconut milk or water as needed.

When the potatoes are soft, season with the tamarind water, palm sugar, and salt.

Add the roasted peanuts, cover, and let the curry come to a boil.

Once the curry is boiling, ladle into bowls and serve.