This is a very rich curry of beef stewed in coconut milk and massasan curry paste, studded with potatoes, peanuts and carrots. The flavor emphasis is on sweet and sour, rather than super spicy. Massaman curry paste can be found in most Thai fresh markets, or just ask the beef butcher where to find it.
In a pot, add the coconut milk and beef. Heat the beef to a simmer and stew until almost tender, about two hours.
Add the curry paste, stir until combined. Add the potatoes, carrots and potatoes. Stir.
Add 1/4 cup palm sugar, 1/2 cup tamarind juice, a few tablespoons fish sauce, 1 tablespoon salt and chopped peanuts. Stir well and contitue to cook for about another hour.
Slowly cook the curry, scraping the bottom of the pot often. When the potatoes are tender, give the curry a taste. Texturally, the curry should be thick and rich. Cook the curry more if too thin. The curry should also have a balanced sour (tamarind juice), sweet(palm sugar) and salty(fish sauce) taste; add the appropriate ingredients if needed.
When the curry is decided to be done, mix in the whole peanuts and serve with steamed rice.