Gather all ingredients.

Inspect several canning jars for cracks and rings for rust, discarding any defective ones. Immerse in simmering water until needed. Wash new, unused lids and rings in warm soapy water.

Bring vinegar, sugar, and salt to a boil in a medium saucepan over medium heat. Boil until sugar dissolves, about 10 minutes.

Place cucumbers, onions, and bell peppers into a large glass mixing bowl. Pour brine over top and toss vegetables for several minutes.

Transfer vegetables and brine to the sterilized jars; don’t worry if the brine doesn’t cover the vegetables. Refrigerate for 1 to 4 days before eating.