Thoroughly rinse 1 cup rice in cool water, drain well. Repeat process until water runs clear. Drain well.
Place rice in heavy saucepan. Add cold water. Heat to boiling. Reduce heat to low. Cover and simmer 20 minutes or until liquid is absorbed. Do not lift lid during cooking.
Remove pan from heat and let stand covered for 10 minutes. Place rice in non metallic bowl; stir in rice vinegar and seasoned rice vinegar.
Sprinkle mixture over rice and gently stir with a wooden spoon until rice glistens. Spread rice over the bottom of a large, shallow baking pan.
Cover rice with damp towel until needed (up to 3 hours), but do not chill.
Shrimp Sushi Rolls
With damp hands, form 2 tablespoons sushi rice into a slender oval ball, about 2" long x 1" wide. Gently press the bottom of the finger sushi with your thumb to give it a slightly humped look. Continue making sushi rice balls, rewetting your fingers as necessary and placing the sushi on a damp cutting board. Set aside, covered, in a cool place.
Run a bamboo skewer through each shrimp from the head to the tail, just under the shell.
Cook shrimp in boiling salted water about 3 minutes, just until cooked through. Immediately plunge shrimp into ice water to stop the cooking.
Drain and dry shrimp. Remove skewers and peel off shells. Butterfly each shrimp from the head down to, but not through, the tail. Remove any dark vein, if present.
Dab wasabi paste, to taste, on the top of each rice ball. Drape butterflied shrimp over the top of each sushi rice ball. Serve with soy sauce and pickled ginger.