You may realize that your greens are still tough after being cooked long enough. In this case, there are a few measure you can take to tenderize your greens:- 1. Using some type of acid - add 2-3 tablespoons of apple cider vinegar or the juice of half a lemon during cooking. The vinegar or lemon juice acts as a tenderizer, introduces tangy flavor and helps balance the bitter taste of the collard greens. 2. Using baking soda - boil some hot water in a large pot and 1-2 pinches of baking soda. The water will foam at this point but do not worry. Add the chopped greens to the pot, blanch for 5 minutes then use a sieve to rinse. This method also helps preserve the color. 3. Cutting off the stems - get rid of the stemmy parts as much as possible during the cutting process. The stems tend to be hard and chewy so getting rid of them helps keep the overall dish tender. 4. Cook longer- finally you can tenderize your collards by adding one more cup of broth and cooking them for 30 minutes longer.