01 -
Slice up your peppers and onions, then toss them in a big bowl. Make sure to mix them around so they're evenly combined.
02 -
Grab a medium-sized saucepan and pour in the two vinegars. Add the white sugar, mustard seeds, celery seeds, turmeric, salt, black pepper, and chili flakes if you're using them.
03 -
Put the pan over medium heat and stir as the mixture comes to a gentle boil. Keep stirring until the sugar completely dissolves.
04 -
Carefully pour that hot liquid over the sliced peppers and onions in your bowl. Stir well to make sure the veggies are fully coated.
05 -
Let the relish mix sit and cool to room temperature. Once it's cool, transfer it to a clean jar or container with a snug lid.
06 -
Refrigerate the relish for at least a full day before you dig in. This break gives all the flavors time to blend nicely.