Slice the jalapeños into rounds using food-safe gloves and a sharp knife.
Add the sugar, apple cider vinegar, garlic powder, celery seed, turmeric, and crushed red pepper flakes to a Dutch oven over medium-high heat. Bring to a boil, then reduce the heat and simmer for 5 minutes, stirring occasionally.
Add the sliced jalapeños, bring the mixture to a boil, then reduce to a simmer, and cook, stirring occasionally, for 5 minutes.
Using a slotted spoon, remove the jalapeños and place them in a glass jar.
Bring the remaining liquid to a boil, and reduce for about 5 minutes.
Carefully ladle syrup over the jalapeños. Let cool completely.
Cover with a lid and refrigerate for a few days before eating (if you can refrain).