Cut the red onion in half then thinly slice it using a mandolin or knife. This should yield about 3 cups of onions. Transfer to a clean and sterilized glass jar.
In the jar with the onions, add garlic, white peppercorns, Szechuan peppercorns, and dried chilis.
In a pot, combine white vinegar, water, salt and sugar. Bring to a simmer over medium heat. Once the sugar and salt has fully dissolved. turn off the heat.
Pour the mixture over the red onions in the glass jar. Using a spoon or spatula, push the red onions down so that they are fully submerged.
Set the onions aside to cool down completely. Once cooled, cover with a tight lid then transfer to the fridge.
Serve and enjoy chilled!
