Remove the skin from the onion and slice very thinly, in a consistent thickness. You may finding using a mandoline helpful. Slice jalapeno in thin rounds.

In a small saucepan, heat water, vinegar, salt, and honey, over medium heat. Bring it up to a simmer, stirring gently, and then immediately turn off the heat. Allow to cool for 1 minute.

In the bottom of a glass jar (needs to be at least 26 oz.) add half of the sliced red onions, jalapenos, peppercorns, and smashed garlic. Repeat to use up the other half of ingredients. This ensures that all the onions and flavorings mesh together. 

Pour hot vinegar mixture over top. Allow to sit at room temperature for one hour. 

Enjoy right away or secure lid and place in the fridge to cool.