Combine cucumber and onion slices in large bowl. Layer with salt and cover with ice cubes. Let stand 1 1/2 hours; drain and rinse. Place remaining ingredients in large sauce pot and bring to a boil.
Add drained cucumbers and onions and return to boiling.
Pack hot into 1 1/2 pint jars, leaving 1/4" head space. Remove air bubbles. Adjust caps. Process 10 minutes in boiling water bath.