Pickled Red Onions for Pork Carnitas

I have discovered a deep, abiding love for pickled red onions with my pork carnitas. The sweetness and acidity is just a perfect accompaniment for the rich, meaty meal.

1 small to medium red onion
1/2 cup hot tap water
1/2 cup apple cider vinegar (can also use just white vinegar if you wish)
1-2 Tbsp sugar
1 tsp salt
sliced hot pepper of choice if you like a little heat

1. Run your tap water as hot as it gets. Put 1/2 cup of hot water in a jar, then add 1-2 Tbsp sugar and the 1tsp salt. Put lid on and shake to dissolve salt and sugar. 
2. Add 1/2 cup apple cider vinegar  and sliced pepper if using.
3. Slice red onion thinly (mandolin is great for this--fast and consistent) and tuck into jar so it is covered by the liquid. Let it sit until it is room temp (5-10 minutes), then you can put the lid on and put it in the fridge until ready to use. Will keep about 2 weeks.