On medium heat bring to boil the vinegar and water. Turn off stove and remove mixture from heat. Add the sugar, salt until all is dissolved and let mixture cool completely.
In a thoroughly washed 1 pint jar, add the sliced jalapeno, garlic, peppercorns and oregano. Shoved them all in if you must.
Fill the jar to the top with cooled vinegar mixture making sure the jalapenos are covered. Secure lid tightly and let sit overnight. You can leave it on counter for a few days, the vinegar will preserve the jalapenos but after that you should refrigerate.