Place water and salt in saucepan over high heat.
Meanwhile, heat oil in frying pan over high heat, add onions, and sauté, stirring frequently, until soft and starting to color, about 3 minutes. Add turmeric and cook another 2 minutes. Add coconut milk, bring to a boil, add beans, and simmer for 10 minutes.
When the water is boiling, slowly pour in cornmeal, sitrring constantly. Reduce heat to low and cook, stirring often, until the polenta thickens and starts pulling away from the sides of the pan.
Divide the polenta between the bowls, forming it into soft mounds. Spoon the beans around the polenta and serve immediately.