Parboil onions for 2-3 minutes. Drain well, set aside.
Pour oil into medium saute' pan, set on medium-high heat and cook garlic, parsley stems and red pepper flakes for 5 minutes.
Add onions, chicken stock and parsley, stir well and bring to a boil. Reduce the heat and simmer 10 minutes.
In a small non-stick saute' pan, cook vinegar and sugar over medium heat, stirring contantly with a heat-resistant spatula, wiping edges of pan clean as you stir, until mixture is thick and coats the back of a spoon (2 minutes).
Add butter and stir until well mixed. Pour sauce into saute' pan with onions. Mix well and cook over medium-low heat for 5 minutes.
Serve warm or at room temp. Enjoy! -Diana
Submitted by Diana Bogue Contributed on: and modified on Tuesday December 4th, 2007