Simmer these vegetables in a vinegar solution for 10 minutes. Nibble these pickled vegetables before a meal or put them into a taco.
Combine vinegar, sugar, and salt in a medium saucepan with 3 cups cold water; bring to a boil over high heat and stir to dissolve sugar. Add carrots, onions, and jalapenos and reduce to medium-high heat. Simmer until carrots are just tender, about 10 to 12 minutes. Pour into a medium bowl; set aside 10 minutes. Cover and refrigerate. Keeps for up to 2 weeks.