I truly enjoy brown rice sushi. Their white counterparts just don't cut it for me anymore- less flavorful & satisfying. The trick is in the preparation of the rice which must be nice & sticky but not mushy. This is much tougher to accomplish with brown rice. After much trial & error and pouring through various recipes online, I finally found a recipe that works at GlobalGourmet.
Vinegar Sauce (for 3-4 cups cooked short grain brown rice)
2 T. rice vinegar
4 teaspoons sugar
1 heaping teaspoons salt
To make the sauce, combine the vinegar, sugar and salt in a cup, and mix well until the sugar and salt are fully dissolved. The sauce should become clear. You can also warm up the sauce on the stove or in the microwave to more easily dissolve the salt & sugar.
Take the cooked rice and empty into a casserole dish. Avoid digging or scooping the rice out of the cooker, as this will damage some of the grains. It helps, however, to run a rice paddle or spatula around the edges of the cooked rice to loosen it before turning it out of the saucepan. Once it is in the casserole dish, gently break up the mass of rice with a few smooth, straight, slicing motions of your spatula. Pour the Sushi Dressing Sauce slowly over the back of your rice paddle or spatula, moving it to and fro over the rice so that the sauce is evenly sprinkled all over the rice.
Mix the rice to distribute the sauce thoroughly.
To preserve the integrity of the grains and avoid mashing them together, do not use circular stirring motions but instead "slice" the rice at an angle with your paddle or spatula, lifting it and turning it over in sections or chunks.
When the sauce is well distributed, begin to fan the rice while continuing to mix it. (You can do this yourself, but it's much easier to have a helper do the fanning while you do the mixing.) Fanning will cool the rice to a usable temperature and also helps evaporate the excess moisture. The sugar will give the grains an appealing gloss, which is an essential characteristic of good sushi rice.
Moisten and wring out a fine cotton cloth such as a thin dish towel or cloth napkin and place it on top of the rice to keep it from drying out. The cloth should rest lightly on the surface of the rice. Keep it covered until you are ready to make sushi with it. Rice covered in this way should remain good for several hours, or until the cloth dries out. Remoisten the cloth if it dries out.