Fill the sink with about 6 inches of hot water and add a ½ cup of apple cider vinegar. Submerge the collard greens into the sink and let them soak for 10 minutes.
Begin removing the stems from the greens. Once you're finished removing the stems, continue to let the greens soak and get started on the cooking liquid.
Add a large pot to the stove over medium heat and drizzle a little olive oil. Add diced onions and season with salt and pepper. Saute for about 5-6 minutes.