Heat half of the coconut milk in a large heavy-bottomed pot or Dutch oven over medium heat until it begins to bubble and separate slightly.

Add the Massaman curry paste to the pot and stir constantly for about 3 minutes until the mixture is very fragrant and the oil separates.

Add the beef cubes to the pot, stirring well to coat the meat in the curry paste, and cook for 3-4 minutes to brown the exterior slightly.

Pour in the remaining coconut milk and the beef broth, then add the cinnamon stick and star anise to the liquid.

Reduce the heat to low, cover the pot, and let it simmer gently for 90 minutes until the beef is fork-tender.

Stir in the potato chunks, onion wedges, and roasted peanuts, ensuring they are mostly submerged in the sauce.

Simmer uncovered for an additional 25-30 minutes until the potatoes are cooked through and the sauce has thickened to a creamy consistency.

Stir in the fish sauce, tamarind paste, and brown sugar, then taste and adjust seasoning to achieve a balance of salty, sour, and sweet.

Remove the cinnamon stick and star anise, then serve the curry hot over steamed jasmine rice.