Mix curry powder with ½ cup water in a small bowl; set aside.
Melt butter in a large pot over medium-high heat; add pork pieces and cook until no longer pink, about 5-6 minutes.
Add cubed potatoes and cook until semi-translucent, about 3-4 minutes.
Add carrot and onion; sauté briefly for 2-3 minutes.
Pour in remaining 2½ cups water; cover and bring to a boil, then reduce heat and simmer 10-12 minutes until potatoes are tender.
Add curry mixture to the pot; stir until sauce becomes creamy and heated through, about 2-3 minutes.
Serve curry sauce immediately over steamed white rice.