Slice sweet onion to ⅓ in thickness. Slice cucumbers to ½ in thickness. Sprinkle cucumbers with sea salt and mix thoroughly. Leave at room temperature for 3 hours.After 3 hours, rinse all of the cucumbers and use your hands to squeeze out the excess water. The more water you can squeeze out, the better. Drain cucumbers in a colander while you prepare the sauce.
On a wide pan add the cooking oil and adjust the temperature to high. Add vinegar, water, sugar, and mustard seed. Once this begins to boil, turn off the heat and stir in the sliced onions, celery seed, and paprika.
Wait for 2 minutes to allow the sauce to cool slightly. Transfer cucumbers from the colander to a large bowl. Pour the sauce onto the cucumbers. Let it cool at room temperature then store in the fridge. Best eaten when cold.
It's better to have more cucumbers in order to make plenty all at once since the wait time for salting the pickles is so long.
Easily lasts in the fridge for several weeks.
Always use clean utensils when serving the pickles. Contaminated utensils will make the pickled vegetables spoil quickly.