Photo taken the day of the Duck Rillette & Pickled Red Onion Tea Sandwich post. The one on the upper right is the one used in the recipe.
The bottom two were variations on boiling the onions with the vinegar and I missed the crunch and the bright colors. The upper left is using just room temperature water and vinegar and the onion flavor was too strong. The upper right was just perfect. I boiled just the water and vinegar mixture and poured it over the red onions.
Here's just the pickled red onion recipe. I have it as a side to my grilled cheese sandwiches, as a topping for salad, and whenever I'm looking for a little acid to a rich or fatty dish.
PICKLED RED ONIONS
1/2 cup water
1/4 cup apple cider vinegar
1 tablespoon sugar
2 teaspoons salt
1. Thinly slice onion. (Use a mandoline slicer to get thin and even slices.)
2. Put vinegar, water, salt, and sugar in a saucepan and bring to a boil.
3. Pour hot vinegar mixture over the slice onion. Leave out at room temperature for 1 hour.
Store the pickled red onions in the refrigerator.