Pour water, 1/2 cup coconut milk, and rice into a small saucepan. Bring to a boil over medium-high heat, then reduce heat to medium-low, cover, and simmer until the rice is tender, about 20 minutes.
Meanwhile, melt the butter in a skillet over medium-high heat. Add the tofu and cook until golden-brown on all sides, about 5 minutes. When browned, stir in green beans, curry powder, and 1/4 cup of coconut milk. Simmer until the green beans are tender, then serve over rice.