Wash the collard greens thoroughly under cold running water to remove any dirt or grit, then roughly chop them into 2-inch pieces. Place the chopped greens in a large bowl and soak in cold water for 5-10 minutes while you prepare the other ingredients. This soaking helps remove any remaining debris and makes the greens easier to handle. After soaking, drain the greens in a colander but don't rinse them completely—a bit of water clinging to the leaves is actually helpful for cooking.

Dice the bacon into ½-inch pieces and place them in a cold Dutch oven. Turn the heat to medium-low and cook the bacon for 8-10 minutes, stirring occasionally, until it's crispy and most of the fat has rendered. The bacon will flavor the entire dish and create a rich fat base for cooking the greens. While the bacon cooks, dice the sweet onion into ¼-inch pieces and have them ready to add.

Once the bacon is crispy, add the diced onions and 1 tablespoon of salt to the pot. Cook on medium-low for 5 minutes, stirring occasionally, until the onions become soft and translucent. The salt will begin drawing out moisture from the onions and help season the base of the dish. I find that adding salt at this stage helps the onions cook down more evenly and develop better flavor.

Carefully add the drained collard greens from Step 1 to the pot with the bacon and onions. Do not stir at this point—let them sit on top of the flavorful base. The greens will be piled high in the pot, but they'll cook down significantly as they release moisture and soften. Cover the Dutch oven with its lid and reduce the heat to medium-low. As the greens begin to wilt over the first 20-30 minutes, gently push down the uncooked greens from the top and add more of the cooked greens from the bottom, working in batches until all the greens are submerged and cooking evenly.

Cover the pot and let the greens braise undisturbed for 1 hour on medium-low heat. The collards will soften significantly and absorb the bacon and onion flavors. After 1 hour, stir the contents of the pot thoroughly, combining the collards, bacon, and onions so the flavors distribute evenly throughout.

Add the freshly ground black pepper, white vinegar, and red pepper flakes (if using) to the pot and stir well to combine. The vinegar adds brightness and depth that cuts through the richness of the bacon, while the pepper and optional heat from the red pepper flakes round out the flavor profile. I like to taste a small spoonful here and adjust the seasoning if needed—sometimes greens need a bit more vinegar depending on their natural bitterness. Cover the pot again and cook on medium-low for an additional 1 hour. The longer cooking time allows all the flavors to meld together and the greens to become incredibly tender.