Braised Onions

3 lbs. small white boiling onions
boiling water
6 T. unsalted butter
1 C. rich chicken stock
1/2 C. cider vinegar
2-1/2 T. sugar

1. Combine onions in large bowlwith enough boiling water to cover.   Let stand 3 minutes; drain well.  Peel off skins.  Cut small cross in root ends to avoid bursting while cooking.
2. Melt butter in large skillet over medium-low heat.  Add onions (in 1 layer if possible) and cook until browned on all sides, 8-10 minutes, stirring frequently.  Add stock.  Cover and cook until barely tender, 18-20 minutes.
3. Pour in vinegar, sprinkly sugar over top and blend gently.  Cover and cook until onions are tender when pierced with sharp knife, about 10 minutes.  Uncover and increase heat to medium-high and cook until liquid is syrupy, 3-5 minutes.  Serve hot