Rosemary-Parmesan Polenta

1 cup polenta, conventional or instant
2 tablespoons finely chopped fresh rosemary
8 tablespoons butter
1/4 cup Parmesan cheese
salt to taste
pinch of cayenne
dash of red-wine vinegar
1/4 cup olive oil for sautéing

If using conventional polenta, bring 3 cups of water to a boil and whisk in polenta. Reduce heat to a low simmer and cook 20 to 30 minutes, stirring frequently and adding water as needed. Do not worry if the polenta makes large bubbles and loud noises; this is normal. (If using instant, follow package directions.) When finished, stir in remaining ingredients except oil. Pour or spoon polenta into a pie pan or other pan to a depth of about 1 inch. Let cool. (The dish may be prepared a day or two ahead up to this point.) Cut into serving-size squares or wedges and sauté over medium-high heat on one side only in olive oil until crisp.