Pickled red onions are a great topping for tacos, adding a tangy, sweet and crunch to each bite.
Peel and slice the red onion and separate the pieces.
In a small saucepan, heat the vinegar, water, sugar, salt, bay leaf and red pepper flakes on medium. Stir the mixture until the sugar and salt dissolve.
Place the onions in a container that has a lid and pour the mixture on top (mason jars will allow the pickled red onions to keep longer).
Let the onions cool completely, then place in the refrigerator.
Onions will be ready to use after 2-3 hours, but the taste will be better the longer they sit in the pickling juice.
Serve on top of tacos or salads.