1MAKE THE BATTER
Beat the egg slightly with a fork, then add the very cold ice water. I put ice cubes in it to get it really cold. This is the secret of making good tempura. Add this ice water to the egg and mix. Then add the cup of flour, mix with a fork. (It is important to add the ingredients in that order: egg, water, then flour) DO NOT OVERMIX THE BATTER!
Use about 1/4 inch of vegetable oil for frying. I use an electric skillet and heat the oil to 375 degrees. This is crookneck squash. Tongs makes the job easy. Using the tongs, dip the squash in the batter and drop into the hot oil. Fry golden brown on both sides. Remove and drain on paper towels. Sprinkle with Kosher salt.