Oil a small cookie sheet, or something similar, with the sesame oil.
Place the mochi on the oiled pan, and proceed to dribble the sesame oil onto that as well, and distribute it around until it's evenly coated. Set aside.
Mix the rest of the ingredients, and bring to a boil, adding water in small (1oz) amounts to keep the resulting sauce in liquid form. While you are waiting for this to come to a boil, place the sesame oil-coated mochi under the broiler.
When the mochi starts to become crisp, glaze it slightly with the sauce, flipping it, until the sauce in the pan becomes caramelized.
At the very end, remove your broiled mochi, and plate it by setting it down on the plate, and then adding enough sauce to cover (and surround it slightly).
Make sure to work quickly! Not a step but just advice. The glaze will become a thick and sweet shell on the mochi, but if you do not hurry, it will become a lump of caramelized sugary stuff in the pan!