A great, easy dish for a hot summer's day is hiyayakko — chilled tofu with various toppings.
Hiyayakko has been popular since the Edo Period (1603-1868). It was so ubiquitous that “Tofu Hyakuchin,” a bestselling tofu cookbook published in 1782, says that "one need not describe hiyayakko since it is so well known."
You can use either firm (momen) or soft (kinu) tofu, although my preference is to use the firmer momen variety. Whichever one you use, it must be fresh — ideally, you should eat it the day it’s bought. If you have to keep it for more than a day, put it in a container filled with fresh cold water, and change the water at least once a day. (But don’t keep tofu like this for more than a couple of days.) Drain the tofu well before adding the toppings.