This is possibly the quickest, easiest way to transform your meal into something special. It's true - imagine a simple taco, now imagine said taco with pickled red onions on it. Let's think outside this taco for a minute and explore what else you could improve with these onions. Sandwiches, salads, grilled cheese, fried rice, quesadillas, hot dogs - there are many more but I'm starting to get too hungry thinking about it.
I like to keep a jar of these in the fridge and put them on everything. Since I can't have hot sauce, (why are you a nightshade, chile pepper???) I use these instead. They're not spicy at all but fulfill the same need with their sharp, briny punch.
Feel free to add more aromatics if you like - bay leaf, chiles, other seeds. I leave everything free floating in the jar but you can wrap the aromatics up in a piece of cheesecloth to keep things tidy.
Pickled Red Onion
1.5 teaspoon kosher salt
1 teaspoon sugar
1/2 teaspoon black peppercorns
1/2 cup or so white vinegar
1 red onion, thinly sliced
Add kosher salt, sugar, peppercorns and vinegar to a 12-16oz jar. Shake or whisk to dissolve. Add onion slices to jar, pressing down to fit if needed. Top off with water so onions are covered in liquid, if needed. Leave them alone for one hour. After that, they are ready to eat. Store in fridge.