Step 1

Trim, peel and halve 1 large red onion lengthwise (from root to tip). Cut each half lengthwise into 1/4-inch pieces (about 2 cups). Place the onion in a medium bowl and sprinkle with 1 teaspoon of the granulated sugar and 1 teaspoon of the kosher salt. Use your hands to massage the onion, separating the layers, until the onion is softened, about 3 minutes. Pack the onion into a 1-quart mason jar or glass container with a lid.

Step 2

Place 1 1/2 cups distilled white vinegar, the remaining 1/4 cup granulated sugar, and remaining 1 tablespoon kosher salt in a microwave-safe liquid measuring cup or small saucepan and whisk until the sugar and salt are dissolved.

Step 3

Microwave on high until steaming hot, 2 to 3 minutes, or heat on the stovetop over medium heat just until simmering around the edges. Pour over the onion and make sure it is submerged. Let sit at room temperature for at least 5 minutes before serving.