Cook the bacon in a large Dutch oven or heavy-bottomed pot over medium-high heat, stirring until the fat has rendered and the bacon starts to crisp, about 5 minutes.

Add the onion and cook until it begins to turn translucent, about 4 minutes; reduce heat to medium if the bacon begins to brown too much. Season with salt and pepper.

Add the collards to the pot and cook until the leaves begin to wilt, 3 to 5 minutes.

Add the cider, vinegar, bay leaves, and 1 cup of water. Bring to a boil, then reduce the heat to low.

Cover and simmer until the collards are very tender, 1 to 1? hours. Transfer to a serving dish.