Wash and slice cucumbers into 1/4-inch rounds. If using onion, slice thinly. Lightly smash garlic cloves with the flat side of a knife to release oils.

Layer cucumber slices, onion, and garlic in a large mixing bowl. Sprinkle with 1 teaspoon salt and toss gently. Let sit for 10 minutes to draw out excess moisture.

In a medium saucepan, combine apple cider vinegar, water, coconut sugar, and remaining salt. Bring to a boil over medium-high heat, stirring until sugar and salt completely dissolve.

Remove from heat and let cool for 5 minutes. The brine should be warm but not boiling hot when added to vegetables.

Rinse the salted vegetables under cold water and pat dry with paper towels. This removes excess salt and prevents overly salty pickles.

Layer the spice blend (dill, mustard seeds, coriander seeds, peppercorns, red pepper flakes, and thyme) in the bottom of your clean quart jar.

Pack the vegetables tightly into the jar, leaving 1/2 inch headspace at the top. Pour the warm brine over vegetables, ensuring they are completely submerged.

Tap jar gently on counter to release air bubbles. Add more brine if needed to cover vegetables completely. Seal with tight-fitting lid.

Refrigerate for minimum 2 hours for lightly pickled flavor, or overnight for fully developed tangy taste. Pickles will continue to improve in flavor over the first 24-48 hours.

Serve chilled as a side dish, sandwich topping, or snack. Always use clean utensils when removing pickles to maintain freshness.