Grind coarsely (measurements are after ground):
3½ cups cucumbers
1½ cups carrots
1 cup onion
Mix with 2 tbsp canning salt and stir. Let stand 3 hours and drain well.
In pot:
2½ cups sugar
1½ cups vinegar
1½ tsp mustard seed
Bring to boil, add vegetables and simmer for 20 minutes. Sterilize jar and seal at once.