Wash the cucumbers and dry them with paper towels. Dissolve the salt in 2 quarts hot water. Pour the salted water into a large glass container, and submerge the cucumbers in it. Put a plate on top to prevent the cucumbers from floating to the surface. Refrigerate for 24 hours.

The next day, take the cucumbers out of the salted water and rinse them off.

Make the pickling brine: Put the vinegar, garlic, shallots, salt, sugar, and 1 quart water in a medium pot. Combine the mustard and fennel seeds, peppercorns, red pepper flakes, and bay leaves in a sauté pan, and toast over medium-low heat until they start to release their aroma, about 3 minutes. Add the toasted spices to the vinegar mixture and bring it to a boil. Then lower the heat and let the brine simmer for 10 minutes.

Place the cucumbers in a clean, dry glass or ceramic container, and pour the hot brine over them. Use a plate to keep the pickles submerged in the liquid, and place the container, uncovered, in the refrigerator; leave it until the brine cools down. Then cover the container with a lid and refrigerate for 1 week. (The pickles will be good to eat in a week and great in a month. Store them in the refrigerator.)