| dish: side|
In a large straight-sided skillet add onion and oil over medium heat. Cook, stirring occasionally, until onions are translucent, about 3 minutes. Season with salt and pepper. Add the vinegar, and cook until it evaporates, about 30 seconds. Add the collard greens and chicken stock. Bring liquid to a simmer, stirring occasionally. Cover, and cook 15 minutes.