Add all of the ingredients to a bowl and mix well.
Spread the dough out on a cooking sheet, cover with plastic wrap, and roll out to about 17x17 cm with a rolling pin (2 mm thick).
Remove the plastic wrap, cut into fourths horizontally with a knife,and then cut into eighths vertically. See Steps 4 and 5.
Scoop up the cut dough, and line with spaces in between. You can scoop up 2-3 pieces at a time if you can manage it.
Or, wiggle with your knife when cutting to make space in between.
Bake for 13~15 minutes in an oven preheated to 340°F/170°C. Keep an eye on them as they bake to make sure they don't burn.
You can make a thin roasted barley flour and sesame version the same manner. The thin roasted barley flour will absorb moisture more, so use lots of milk.
When using mochiko, it closely resembles joshinko with little distinction, but it easily burns (and swells).
Story Behind this Recipe
I found ginger rice crackers at the snack aisle of a supermarket. I have eaten them before when I received them as a gift, and so when I found them, grabbed them without a second thought. I usually don't buy these, but there was something about the ginger that intrigued me. I wanted to try making it at home, and finally settled on this recipe.
If you have difficulty mixing the dough in Step 1, add in a bit of milk while keeping an eye on it. Use the exact amount of baking powder listed. It will become crispy if you add too much. It will slightly harden, but it's ok. Please adjust the baking time according to your oven.