This recipe is from Martha Stewart Living. I would suggest using Japanese or English cucumbers because they are extra crunchy. They also suggest using yellow summer squashes.
2 pounds cucumbers, cut into 1/8 inch slices (about 6.5 Cups)
2 heaping Tbs coarse salt
1 medium white onion, thinly sliced
2 C ice cubes
3 C cider vinegar
2 1/4 C sugar
1 tsp whole mustard seeds
3/4 tsp celery seeds
3/4 tsp whole black peppercorns
1/4 tsp turmeric
1/4 tsp crushed chili pepper flakes (I used three small, dried hot chilis- one for each jar)
Toss cucumbers and onions with salt and ice cubes in a large colander. Place over a bowl and refrigerate for three hours, or overnight, tossing occasionally. Drain, and rinse.
Bring vinegar and all other ingredients to a boil in a large pot. Add the cucumbers and onions, and bring back to a boil. Remove from heat and ladle into three sterilized, hot pint jars. If you are planning to keep these for more than a month, you should can them according to the directions that come with your canning jars. If not, refrigerate and serve!