From https://www.theperfectloaf.com/rye-sourdough-and-smorrebrod/
"For the sandwiches you could get away with half a red onion, but I used a full onion and saved the rest in the fridge for more sandwiches or potatoes later in the week.
The pickled onions will keep refrigerated for about a week covered in the brine.
You could use any combination of vinegar you’d like, I used mostly white vinegar with some red vinegar to give them a bright pink color.
Ingredients:
1/2 red onion, sliced very thin
3/4 cup white distilled vinegar
1/4 cup red vinegar
1 garlic clove, halved
2-4 sprigs of thyme
very small pinch of red chili flakes
1/2 tsp raw sugar
small pinch of salt
Method:
Place all the ingredients except the onion in a small saucepan and bring to a boil
Once boiling, pour the hot brine over the red onions in a small bowl, or alternatively, directly in their final glass storage jar (make sure the onions are completely submerged)
Let sit at room temperature for at least 30 minutes before using, preferably 1 hour or more"
"For the sandwiches you could get away with half a red onion, but I used a full onion and saved the rest in the fridge for more sandwiches or potatoes later in the week.
The pickled onions will keep refrigerated for about a week covered in the brine.
You could use any combination of vinegar you’d like, I used mostly white vinegar with some red vinegar to give them a bright pink color.
Ingredients:
1/2 red onion, sliced very thin
3/4 cup white distilled vinegar
1/4 cup red vinegar
1 garlic clove, halved
2-4 sprigs of thyme
very small pinch of red chili flakes
1/2 tsp raw sugar
small pinch of salt
Method:
Place all the ingredients except the onion in a small saucepan and bring to a boil
Once boiling, pour the hot brine over the red onions in a small bowl, or alternatively, directly in their final glass storage jar (make sure the onions are completely submerged)
Let sit at room temperature for at least 30 minutes before using, preferably 1 hour or more"