Add the vinegar, water, sugar, and salt to a small saucepan and whisk.
Bring the mixture to a boil and remove from heat once the sugar and salt have dissolved. Set aside.
Next, prepare two clean mason jars for the refrigerator pickles. Divide the fresh dill, mustard seed, white onion, coriander seeds, and peppercorns into the two mason jars.
Slice cucumbers into spears, making sure they aren’t too tall for the Mason jars. Then, separate them into the Mason jars.
Carefully divide the vinegar mixture into both jars, making sure that the cucumbers are covered with the liquid.
Let the vinegar mixture cool before covering the the jars tightly. Then, shake the contents of the jar until mixed.
Place the jars in the fridge for 24-48 hours before trying the pickles.