Peel and mash the avocados. Mince the green onion. Remove the seeds and mince the jalapeno pepper and add to the avocado with the onion, salt and lemon juice. Mix well and refrigerate for several hours before serving.
Depending on your taste and the heat of the pepper you have you may want to use a whole Jalapeno Pepper.When storing in the fridge, place the plastic wrap right down on top of the guacamole, sealing it off from any air that might be in the dish. This will keep it from browning until you are ready to serve. Lemon juice helps, but this works best.