Prepare your jars and lids by washing in warm, soapy water, and rinsing well. Place your jar rack into a small water bath canner or large pot. Add water to cover the jar and boil for 10 minutes to sterilize. Turn off heat and add the lids to the warm pot to soften.
Rinse the string beans and cut into 4-inch pieces to fit in the jar.
Combine the salt, vinegar, and water and a large pot. Bring to a boil, reduce the heat, and simmer for 10 minutes.
Remove the warm jars from the canner, drain, and place on a kitchen towel.
To each jar, add 1/4 teaspoon red pepper flakes, 1 clove of garlic, and 2 teaspoons of dried dill seeds or 1 head of dill.
Pour the hot pickling liquid over the string beans, leaving 1/2 inch of headspace. Remove air bubbles with your bubble popper and wipe the rim. Add the lids.
Place the jars back into your water bath canner, adjust the water level so it is 2-inches above the top of the jar. Bring the canner to a boil, and process in a hot water bath for 10 minutes.
Turn off the heat, allow the canner to cool, remove the jar, and place it on a kitchen towel to cool. Check seals and store in a cool, dark location. Allow 2-4 weeks for the dilly beans to develop their flavor.
Once the jar is open, store in the refrigerator for up to 2-weeks. Recipe makes 4 pints.