To fire-roast the red peppers, place them over a high flame on a stove-top burner and roast, turning occasionally, until the skins turn black on all sides. Place the peppers in a medium bowl, cover with plastic wrap and allow to steam for 10 minutes. Peel away the blackened skins from the peppers. Cut away the stems and then seed, core and coarsely chop the peppers. Place them in a food processor and puree until smooth; reserve to the side.
In a heavy-bottom medium pot, bring 8 cups water, thesalt and the roasted red pepper puree to a boil. Add the stone-ground cornmeal in a gentle stream, whisking or stirring vigorously in the same direction as you pour it in. Reduce the heat to medium-low and simmer, stirring continuously for 2 to 3 minutes. Cook the polenta for 35 to 40 minutes, stirring every few minutes and scraping the bottom of the pan to prevent it from sticking. When the polenta is thick, glossy and pulling away from the side of the pan, add the Pecorino Romano and butter, stirring quickly to incorporate. Pour the polenta into a medium serving dish and serve immediately.