The Biology Man wipes these out every year.
Wash, snap, and cut yellow was beans as soon as they come in from the garden. Boil for 10 minutes. They should still be crispy.
Pour off water, but keep it.
Mix 3 cups of reserved water, 3 cups vinegar, and 3 cups of sugar. Add a tablespoon of mustard seed. Pour brine over beans (still in pot.) Bring to a boil. Turn off. Pack in pint jars with juice and seal.
Save brine any left over brine in a jar in the fridge for next time. Add it to the new brine.