Wash and thinly slice the cucumbers and sweet onions. Place them in a large mixing bowl.
In a saucepan, combine apple cider vinegar, sugar, salt, mustard seed, and turmeric. Bring to a gentle boil, stirring until the sugar dissolves.
Pour the hot vinegar mixture over the cucumbers and onions, ensuring they are fully submerged.
Let the mixture cool to room temperature, then transfer it into sterilized glass jars.
Seal the jars and refrigerate for at least 24 hours before serving to allow the flavors to develop.
Enjoy your sweet pickles with sandwiches, BBQ dishes, or as a crunchy snack!