Wash the collard greens thoroughly under cold running water to remove any dirt or grit. Pat them dry with paper towels or a clean kitchen towel. Remove the tough center stems and discard them, then chop the leaves into bite-sized pieces, about 1/2-inch width. Set aside on a cutting board or in a bowl.

Heat the extra virgin olive oil in a large pot or deep skillet over medium heat until it shimmers, about 1-2 minutes. Add the chopped collard greens in batches, stirring occasionally, until they begin to wilt and reduce in volume, approximately 5 minutes. This initial cooking breaks down the greens and allows them to absorb the oil's robust flavor. I like to use Californian olive oil here because its bold flavor complements the earthiness of the collards beautifully.

Pour 1 cup of water and the apple cider vinegar into the pot with the wilted greens, stirring to distribute evenly. Cover the pot with a lid and reduce heat to medium-low. Simmer for 25 minutes, allowing the greens to become tender and the liquid to infuse them with tangy brightness. The vinegar will add the perfect acidic balance to cut through the richness and natural bitterness of the greens.

Remove the lid from the pot and stir in the drained Great Northern beans, mixing well to combine them with the braised greens. Sprinkle the salt and red pepper flakes over the mixture and stir to distribute the seasonings evenly throughout. Taste and adjust the heat level with more red pepper flakes if desired—I prefer to start with 1/4 teaspoon and add more gradually so I can control the spice level to my preference.

Simmer uncovered for 1-2 minutes more to allow the beans to warm through and the flavors to meld together. Transfer to a serving dish and serve hot. The dish can be enjoyed as-is or with cornbread, rice, or other sides.