If you are going to publish a recipe you need to clarify!
When do you add the vinegar and too what?
The Caper Brine?
Sugar to the toasted dry items? I don't think so.
Let me correct the recipe:
Rinse the rice 5 times, then drain in a colander and let dry for 15 minutes.
Cook the rice in a rice cooker according to the manufacturer's instructions. Alternatively, in a medium saucepan, combine the rice with 2 cups of cold water and bring to a boil over high heat. Cover and cook over moderate heat for 10 minutes. Reduce the heat to low and cook for 10 minutes longer. Remove from the heat and let stand, covered, for 15 minutes.
Cream Cheese Mixture:
Mix the wasabi powder and 2 tablespoons water in a small bowl until dissolved. Add the cream cheese to the bowl and use a rubber spatula to fully incorporate the wasabi.
Toast until fragrant. Transfer to a small plate to cool.
White sesame seed.
Dried minced onion.
Dried garlic flakes.
Mix together well.
Combine soy sauce, and then whisk in (or use your chopsticks to blend in) as much or as little wasabi as you’d like. (Always start with less and add more, if you’ve never used wasabi!)
Place the warm rice, wasabi cream cheese, seasoning mix, and sliced fish in close proximity. Wet your hands with water. With your dominant hand, grab less than a Ping Pong ball’s worth but a little more than a shooter marble’s worth of rice. Gently squeeze it so it’s about the length and diameter of a fat wine-bottle cork. Too much squeezing makes the rice like clay, too little and it falls apart. (Luckily the recipe above makes enough rice for you and your guests to practice.) Once the rice ball is formed, slide it a bit lower in your palm and hold onto it. Pick up a slice of fish with your non-dominant hand. With your dominant pointer finger (rice ball still clutched) swipe a little wasabi cream cheese onto the fish. Gently press the rice ball onto the cream cheese–smeared fish in your non-dominant hand. Flip the nigiri fish-side up in your non-dominant hand, and gently apply pressure with two fingers of your dominant hand and a cupping motion from your non-dominant hand. Rotate the fish and rice ball 180 degrees and repeat, so as to round off the corners and strongly adhere the fish to the rice ball.
Don't forget the dipping Sauce!