In a 4- to 6-quart pan over medium-high heat, bring 9 cups water to a boil. Whisk in salt and polenta. Reduce heat and simmer, stirring occasionally, until polenta is smooth to taste, 25 to 30 minutes. Remove from heat and stir in butter and parmesan cheese; add pepper to taste. Cover and keep warm over low heat.
Greens, San Franciso, California