This one is simple and tasty. I add this to steaks, burgers, and many more. You only need a tiny amount since it is quite sour. (Unless you're a fan of sour side dishes like yours truly, then you might want to eat a quarter of the jar in one go!)

In a fridge, it lasts for months. Add more sliced red onion later, don't waste the vinegar! The second batch would taste sweeter and milder.