These pickled onions are crisp, tangy, and slightly sweet. We use a combination of fresh lime juice and apple cider vinegar. You can use just one acid, but we’ve found the combination adds a touch more complexity. There’s a lot of elbow room when it comes to adding spices or additional flavors. We use cinnamon sticks, cloves and red pepper flakes. Keep it clean and simple and add none or add a combination of the following: cinnamon sticks, whole cloves, crushed red pepper flakes, whole garlic, star anise, bay leaf, mustard seeds, fresh ginger slices, fennel seeds, coriander seeds or cumin seeds.
1 large or 2 medium red onions, halved and thinly sliced
2 cinnamon sticks
6 whole cloves
Pinch crushed red pepper flakes
1 cup (240 ml) apple cider vinegar
1/2 cup (120 ml) freshly squeezed lime juice
3 tablespoons to 8 tablespoons (38 to 100 grams) sugar, see notes
1 tablespoon kosher salt
Add sliced onions to a medium bowl. Pour enough boiling water over onions so that they are covered. Count to 5 then drain. Add the onions to glass jars (or a food safe glass container with lid).
Toast cinnamon, cloves, and the red pepper flakes until fragrant in a small saucepan over medium heat, 3 to 5 minutes. Whisk in the vinegar, lime juice, 3 tablespoons of the sugar, and salt.
Bring to a simmer and cook until the sugar and salt have dissolved, 1 to 2 minutes. Taste for sweetness then add more sugar as needed.
Pour brine over the onions. Allow to stand at room temperature until cooled. Serve or cover and refrigerate 2 to 3 weeks.