Heat the butter in a skillet over medium heat and sautÈ the onions with the salt and cayenne, stirring often, for 4 to 5 minutes, or until soft. Add the tomatoes, parsley, and garlic and sautÈ, stirring often, for 4 to 5 minutes, or until tomatoes are soft. Add the broth and simmer, stirring occasionally, for 6 to 7 minutes.
Remove from the heat.
Let rest for about 5 minutes before serving. The sauce will keep, covered, in the refrigerator for up to 1 week.
Yield: 1 3/4 cups