Peel and slice the carrots into ¼-inch thick slices. Slice the red onion and jalapeño into ¼-inch thick slices as well.

Add the water, vinegar, oil, cumin, oregano, salt, and pepper to a pot. Bring the brine to a boil.

Carefully add the sliced vegetables to the boiling brine, then continue to boil for about 5 minutes.

After boiling for 5 minutes, remove the pot from the heat and carefully transfer the vegetables and all of the brine into jars or another heat-proof container.

Store the pickled carrots in an air-tight container in the refrigerator for 3-4 weeks.