Wash the green beans well. Trim the stem ends off each bean. You want them snappy, so do not over-trim.
Pack the green beans tightly into clean, pint-sized canning jars. Place two garlic halves, 1/4 teaspoon red pepper flakes, one dill head (or 1 teaspoon dill seed), 1/4 teaspoon black peppercorns, and 1/4 teaspoon coriander seeds into each jar alongside the beans.
In a medium saucepan, combine the vinegar, water, pickling salt, and sugar. Bring this brine mixture to a rolling boil over high heat, stirring until the salt and sugar dissolve completely.
Carefully pour the hot brine over the beans in the jars, making sure the liquid covers the beans completely. Leave about 1/2 inch of headspace at the top of the jar.
Tap the jars gently on the counter to release any trapped air bubbles. Wipe the rims clean. Seal the jars with lids and rings, tightening them to fingertip tight.
Let the jars cool to room temperature on the counter. Once cool, place the jars in the refrigerator. These dilly beans are ready to eat after 24 hours, but the flavor improves after 3 days. Store them in the refrigerator for up to 2 months.
Notes
For the crispiest dilly beans, you can add 1/4 teaspoon of pickling lime or a small grape leaf to each jar before adding the brine.
If you prefer a classic dill flavor without the heat, omit the red pepper flakes.
This is a refrigerator pickle recipe; it is not safe for long-term shelf storage without proper water bath canning procedures.