Wash two mason jars and lids in hot soapy water, rinse and dry.
Clean the English cucumbers well then trim the ends before slicing them into thick coins.
Place four cloves of smashed garlic, a large handful of fresh dill, 1 1/2 teaspoons of coriander seeds, 1 1/2 teaspoons of whole peppercorns, and 1/4-1/2 teaspoon of crushed red pepper flakes, to taste, into each jar.
In a large bowl, combine the sugar, kosher salt, and white vinegar together.
Whisk vigorously until the sugar and salt have completely dissolved. Add the water to the mixture and mix well.
In the two clean mason jars, tightly pack the cucumber coins into each jar.
Once full, pour the brine mixture evenly over the cucumbers. Tap the jars on the counter to release any air bubbles and top off the jar with extra water if any cucumbers are exposed.
Place the lids on the jars and screw on the rings until they are tight. Leave the jars in the fridge for 24 hours before tasting.
The pickles last up to one month refrigerated.