Wash the jalapeños thoroughly under cold running water and pat them completely dry with paper towels.

Using a sharp knife, slice each jalapeño into rings about 1/4-inch thick and remove most of the seeds.

In a large pot, combine 6 cups of white vinegar, 6 cups of sugar, and 6 teaspoons of salt. Stir over medium-high heat until the sugar completely dissolves (about 3 to 4 minutes).

Add the minced garlic, red pepper flakes, mustard seeds, and turmeric to the pot, stirring well to distribute evenly. Let it simmer for about 2 minutes.

Increase the heat to high and bring the mixture to a rolling boil for exactly 5 minutes.

Carefully add all the sliced jalapeños to the boiling brine, stirring gently to submerge them.

Reduce heat to medium and let the mixture simmer for 10 minutes, stirring occasionally.

Using a slotted spoon, transfer the jalapeños into clean, hot jars, leaving about 1/2-inch headspace. Pour the hot brine over them, maintaining the same headspace.

Immediately place the lids on the jars while everything is hot and let them sit at room temperature for at least 30 minutes.