What to do with mochi...this version is white, hard and puck-like in shape?
I've actually found this post about mochi. They show the cakes that I've seen in the past and also the shape that I mentioned in my post.

It seems like you can:


grill them - they will brown a bit and rise.
boil them - they won't rise
microwave them


And the ways to serve it is with:


Butter+soy sauce (an interesting combo that I will try)
Rolled in ground sesame seeds + sugar or salt.
Rolled kinako (toasted soybean powder + sugar.)


UPDATE

Boiled

I cut them into about 1 inch x 1 inch pieces and threw them in boiling water. Boiled them for about a minute or so...then removed them to a bowl of cold water to stop the cooking process.

Dressings

I tried butter+soy sauce (1 TBSP melted : 1/4 tsp soy sauce) - It's actually pretty good!

I also ground up some black sesame seeds with sugar (1 TBSP : 1/2 tsp sugar)...this was actually my favorite of the two.