Cut the cucumbers, onions and pepper as thin as you can (this is where my veggie slicer comes in handy)Add salt to the veggies and set them asideIn a small saucepan, add vinegar, sugar, celery seed and mustard seed and bring it to a bowl.Remove the sauce from the heat and let it cool for at least 1 hour or more.Stuff the veggies mix into wide mouth mason jarsOnce the sauce has cooled, divide the mixture up between each mason jar salad.Optional: Seal the top of the jar using a food processor if you plan to store it for a long time.Store these jars in the refrigerator for up to 2 months or possibly longer if you sealed the jars.