This is the trickiest part of making sushi and the best way to get the right consistancy is to only use Sweet Mirin (no vinegar sugar combos please) hot sticky rice and fan for about 8-10 minutes while constantly turning (like folding the mirin into the rice) you can use a mini electric fan on low but a second pair of hands fanning with a towel works best.

I highly recommend getting a rice cooker for proper sticky rice - because while it can be made on the stove top it must be watched or it burns or is too soupy and the consistancy of a rice cooker can't be beat!