Shrimp Toast

8 slices white bread, crusts discarded (stale is best, but you can toast the bread on the light setting of your toaster a couple times to dry them out)
1 pound shrimp, peeled, deveined and minced
3 fresh water chestnuts or if not available 1/4 cup minced jicama — I don’t like canned water chestnuts as they always have a “tinny” taste
the white part of 1 large scallion/green onion, minced
1 teaspoon salt
1 tablespoon shiaohxing or dry sherry
1 large egg white, beaten until foamy
3 tablespoons cornstarch
1 1/4-inch thick piece of ginger, peeled and minced
3 tablespoons water
2 teaspoons sesame oil
oil for greasing knife
oil for deep-frying (peanut or other high-temp oil)