Wash greens in a large bowl of cold water, swish, drain, and repeat until water runs clear. Dry well. Remove tough stalks and center ribs; discard bruised or yellowed leaves. Stack leaves, roll into a cigar shape, and slice into 1-inch ribbons or coarsely chop. If keeping stems (e.g. collards), chop them separately — they need more cooking time than the leaves. Mince or thinly slice garlic. Measure out your braising liquid (water, stock, or broth) and have it ready before the pot gets hot.

Heat a heavy pot over medium heat, then add 1–2 tbsp fat (olive oil, butter, or bacon fat). If using bacon, cook until crisp and fat renders, about 4 minutes, then remove and set aside. Add garlic and/or onion; garlic alone takes 30–60 seconds, onion with garlic about 5 minutes. Stir in any spices and cook 1 minute until fragrant. Add greens — they'll be voluminous but wilt down fast. Turn with tongs to get leaves in contact with the heat. Pour in ⅓–½ cup water or stock, add vinegar if using, season with salt and pepper, stir, and partially cover. Reduce to low or medium-low. Simmer, stirring occasionally. Tender greens like mustard greens: 5–6 minutes. Heartier greens like collards: 10 minutes minimum, up to 1 hour for deep tenderness. Check liquid every 10 minutes and add more broth or water if the pot looks dry. Greens should stay moist but not soupy. Light browning on leaf edges is fine; sticking or burning means the heat is too high or the pot needs more liquid.

Greens are done when leaves are fully tender with no tough or stringy resistance. Taste a piece — it should be soft and yielding. Color will deepen and volume will reduce significantly. If hearty greens like collards still feel tough, add a splash of liquid and cook 5–10 more minutes. Off the heat, stir in 1 tbsp unsalted butter for richness. Add reserved bacon if using. Taste the pot liquor and adjust with salt, pepper, or a splash of vinegar. Serve from the pot. Keep a small amount of liquid in the pot throughout — going dry causes scorching, not braising.