Use fresh cucumbers; wash and slice. Slice onions. Mix vegetables with salt and let stand 1 hour.
Drain and rinse with 2 cups cold water. Combine vinegar, sugar, celery and mustard seeds and heat to boiling. Cook 3 minutes.
Pack vegetables into jars, add hot vinegar mixture, leaving 1/4" headspace. Seal at once and process in boiling water bath for 10 minutes.
Cool and store.
Submitted by: CM