I favor patties over balls as they have more surface area and become crisp and firm. Balls tend to be a bit mushy inside. I suggest making a double recipe as it's hardly more effort than a single - most of the work is in set-up and clean-up.
Recipe: There are many variations so the list of vegetables
here should be considered typical but not mandatory (though nearly all have
carrot). Many other firm vegetables could be used as well and seasonings
can be changed.
Start with blocks of regular Soft tofu and cut into pieces that will result in the desired size (see below). Why not start with Firm tofu which already has less water? Because then it wouldn't be Japanese, now would it?
Your press board should be somewhat slanted so liquid will drain
off into the sink (retired cutting boards are great for this purpose). Most
people use a dishtowel or cloth napkin instead of the bamboo mat shown in the
photo (which drains faster but leaves a pattern on one side). Each of two 19
ounce blocks of tofu has been cut into thirds and set on the mat. If you're
doing only one block set the slices near the sink end and use a spacer (about
the height of the finished blocks - I use a wine cork) between the boards at
the counter end and put the weights just an inch inboard from
directly over the tofu slices.
Here the press is in operation with the top board on and bricks for weights.
Once the tofu was partially pressed I added a third brick across the two.
I let the tofu press for 3 hours and by then it was quite firm and no
more water was dripping out. 4 or 5 hours wouldn't hurt though.
Remove any surface water from the blocks with paper towels. The photo shows
fully pressed blocks. Originally they were 1.3 inches thick and weighed 6.3
ounces each. After pressing they were 0.8 inches thick and weighed 3.8 ounces
The vegetables have been prepped as noted above and lightly fried. The tofu
has been mashed very thoroughly and mixed with all the other ingredients.
The finished mix has been formed into patties and balls and arranged on a
lightly oiled foil, ready to fry.
Heat plenty of oil to 365°F/185°C and fry the tofu to the degree desired. When the balls or patties float to the surface separate them and turn them over once or twice for even frying. Commercially in Japan two deep fryers are used, a first at about 340°F/170°C and the final at about 385°F/195°C. I have found trying to imitate this with a single frier impractical.
Here 6 ganmo balls are frying in my favorite deep fry rig. That's a 14 inch Indian kadhai charged with Olive Pomace oil and fitted with a wire base and draining rack designed for Chinese woks. The geometry of the kadhai is much better than a wok for deep frying and results in less oil splatter than with any other device (they do a lot of deep frying in India and can't afford to waste oil).
Olive Pomace oil provides the same
health profile as regular olive oil but goes to a very high temperature
(460°F/240°C), is more resistant to heat degradation than peanut oil
(1/3 as much polyunsaturated fat) and imparts no olive flavor to the food
you fry in it. For more information see my page
Here finished patties rest on the drainage rack. A final draining on paper
towels will finish the operation. Refrigerated they'll last about a week and
they can be frozen for longer storage. Warming to room temperature and a
quick deep or pan fry will revive them.