Pour the vinegar into a saucepan, add the salt and sugar, and mix them together.

Bring to a boil over medium heat for 8-10 minutes until the sugar has dissolved.

Divide the sliced cucumbers, onions, and red bell peppers between 2 sterilized jars.

Pour the vinegar mixture into each jar over the vegetables.

Place lids on the jars and store them in the refrigerator, keep them refrigerated for at least 24 hours before eating.