quick pickled red onions

A family favorite on SOOOO many things!
I don't know what it is about the warm weather but I want pickled everything, on everything. These are truly simple to make, they get better and prettier the longer they sit, and they pack a punch of flavor to whatever you're eating.
The recipes vary all over the place, these ratios are what's ingrained in my memory for when I'm throwing something together really quickly.
*One red onion
*1 cup of vinegar
*One cup of water
*Not quite 1/3 cup of sugar
*One tablespoon salt
Optional! Caraway seeds, celery seeds, garlic cloves, peppercorns... Really the limit is just what you have on hand or want the flavors to be. I typically don't add anything, but the additions are really fun!
My favorite vinegar combo is half apple cider vinegar and half rice wine vinegar, but you could do ALL WHITE vinegar, all apple cider vinegar, half red wine vinegar half something else.... Any vinegar will do, and playing with them will help you find your favorite combo.
Pour vinegar and water into a pot on the stove and turn heat up to medium
Add sugar and salt and heat until the sugar is totally dissolved, you don't have to boil or simmer but it should definitely be warm!
While the ingredients are warming up in the pot, thinly slice the onion and place them in a jar or a glass container that will close tightly in the fridge. An old pickle or applesauce jar works great for this!
Pour the vinegar solution over the onions, making sure they're fully submerged. Shove em down if you have to.
I let it sit until the liquid comes to room temp and then put the lid on and pop them in the fridge. I don't know how long they'll last, they never last more than a week in our house, I'd say eat em up by around three weeks! I double the recipe (maybe slightly less than double the sugar) if I'm doing two onions at once ☺️
Do you all love a pickled veggie during the summer, too?!