4 cups boiling water
1 tsp. salt
1 c medium-grind cornmeal
Bring about 2 inches of water to boil in bottom of double boiler; reduce to simmer and maintain throughout cooking process.
Into the top pan of the double boiler, set over the simmering water, add 4 cups boiling water. Add salt, then gradually sprinkle in the cornmeal, whisking constantly to avoid lump formation.
Cover and cook until polenta is very soft and smooth, 1 1/4 to 1 1/2 hours, stirring for several seconds every 10 to 15 minutes. (Once cooked, polenta can be covered and saved up to 4 hours and reheated; stir in a bit of water if necessary.)