Ingredients :

• Red onions — These are what give that impressive pink color—yellow or white onions won’t do the same thing, visually or taste-wise. Choose firm onions without soft spots. The fresher they are, the crunchier they will be after pickling. Two large onions are perfect for a standard jar.
• Cider vinegar — Prefer cider vinegar over classic white vinegar. The acidity is rounder, less aggressive, with a slight fruity undertone that pairs beautifully with the onion’s natural sugar. If you don’t have any, white vinegar works, but the result will be sharper.
• Salt — Salt dissolved in hot brine does more than season—it helps slightly soften the onion’s structure and extract its pungency. Use a level tablespoon, not a heaping one. Too much salt makes it inedible; too little and the onions remain too strong.
• Garlic and dried chili — Optional on paper, indispensable in practice. A whole garlic clove (not minced) provides a soft, aromatic base without dominating. A small dried chili brings just enough heat—not enough to burn, just enough for people to wonder what’s in there.