We use these jalapenos to garnish our Bloody Marys, but they can also be used to top sandwiches and burgers.
Bring vinegar, 1 cup water, salt, sugar, cumin, and garlic to a boil in a medium saucepan. Add jalapenos and onions; boil 5 minutes. Let cool completely, about 45 minutes. Refrigerate in an airtight container at least 1 week or up to 1 month.