Wear gloves. In a large pot, combine the sugar, vinegar, turmeric powder, and garlic powder (if using). Bring to a boil over medium-high heat, stirring until the sugar dissolves.
Add the sliced jalapeños to the pot. Reduce the heat to low and simmer for 20-25 minutes, or until the jalapeños are slightly softened and translucent. Stir occasionally to prevent sticking.
Remove the pot from the heat and let the jalapeños cool slightly in the syrup. As they cool, the syrup will thicken.
Using a slotted spoon, transfer the candied jalapeños to sterilized jars, leaving about 0.5 inch of headspace. Pour the syrup over the jalapeños, ensuring they are completely submerged.
Seal the jars and let them cool completely. Store in the refrigerator for at least 2 weeks before enjoying. The flavor will improve over time.
Notes
Candied jalapeños are great on crackers with cream cheese, in tacos, on pizzas, or even stirred into scrambled eggs!