How to Make Oshi Sushi
Oshi sushi is extremely easy to make, as that is what its intended purpose was. Oshi sushi is kind of like making nigiri sushi, only instead of making it by hand, as with nigiri sushi; you place all of the ingredients into a box mold, press them down, and cut them.
You should prepare as many of the ingredients as you can before hand so that all you have left to do is assemble the oshi sushi once you are done.
Cut the Fish, Meat, Vegetables or Other Ingredients
You can cut your ingredients however thick you would like, but I'd recommend cutting them not thicker than 1/4" thick. When cutting fish, you want to cut across the lines in the fish, as it not only cuts easier, but it also looks better.
Begin Assembling Your Sushi
The first thing you should be concerned about is the rice sticking to your fingers and the box mold. To stop this from happenning, you should dip your hands in warm vinegared water before touching the sushi rice. It helps to prevent it from sticking to you. You can also run your wet fingers around the box mold to stop the sushi from sticking to it as well. You don't want your hands to be wet when working with the rice, you just want them to be damp. Take your Oshi box mold and begin with placing your sushi rice in it. You should fill the mold about 2/3 of the way full, using gentle pressure, depending on how many other ingredients you plan on putting in your sushi. When it comes to ingredients, sushi is meant to be simple, so don't overdo it on the number of ingredients.
Grab the top to your Oshi box mold and place it on top. Place firm pressure on the top and hold pressure for 5 to 10 seconds so that the ingredients stick together well. Be careful to not press too hard on the top though. Usually, one thumb on either side of the top will provide enough pressure.
Cutting Your Oshi Sushi
Some Oshi sushi box molds come with slots cut into the sides so that you can cut your sushi while it is inside of the box mold. Other Oshi sushi box molds may not have the slots, so you will have to remove the oshi sushi and cut it by hand. A sushi kinfe would be the best to cut this with, but a sharp knife will do. Oshi sushi is cut by cutting it in half lengthwise, then putting the two pieces side by side and cutting in half again and repeating until you reach the desired thickness.
Advanced Oshi Making
Once you have mastered making Oshi using your box mold, you can move on to more advanced techniques if you desire. Some people like to add nori around their Oshi style sushi. To do this, you simply line the box with nori, and leave an extra piece for the top before cutting.
Other advanced techniques include making designs inside of the sushi. These designs can become very intricate. The designs that seem to work best take advantage of the symmetrical design of an oshi style piece of sushi. They usually use even numbers of pieces arranged in symmetrical patterns to make a visually appealing piece of sushi. The other trick to making these intricate designs is to remember to use very small pieces so that you can make more elaborate designs.