Rinse and slice cucumber into ¼ inch coins and thinly slice onion. Place in a mixing bowl.
Add kosher salt, mix well, cover with plastic wrap, and place in the refrigerator for 2-3 hours. After each hour, mix well, cover and place back in the refrigerator. This step is important as the salt will draw moisture from the cucumbers, yielding a crisp pickle.
Rinse cucumbers and onions very well, removing salt.
In a medium saucepan add vinegar, dill, garlic, spices, and water and bring to a boil. Lower to medium heat and cook for 3 minutes.
Place cucumber and onion in a sterilized jar. Layer cucumber and onion evenly so that you can pack the jar. Fill with hot brine.
Cover and once the jar comes to room temperature, place in refrigerator.
Store in the refrigerator for up to one month. Ideal if you allow 24 hours before consuming, this gives the pickling liquid time to impart flavor to the pickles.