Wash the green beans thoroughly, trim the ends, and cut them slightly shorter than the height of your glass jars so they fit comfortably inside.
Blanch the green beans in boiling water for about 2 minutes, then transfer them immediately into ice water to preserve their bright color and crisp texture.
Place garlic cloves, dill sprigs, peppercorns, and mustard seeds evenly between clean glass jars.
Pack the cooled green beans vertically into the jars, arranging them tightly while leaving enough space for the pickling liquid.
Combine vinegar, water, salt, and sugar in a saucepan and heat gently until the salt and sugar dissolve completely.
Pour the warm brine over the green beans until they are fully covered, then allow the jars to cool slightly.
Seal the jars and refrigerate for at least one day before eating, allowing the herbs and garlic to infuse throughout the beans.