Remove the strings from the snow peas. Pat the fried tofu with a paper towel to remove excess oil and cut into bite-sized pieces. Slice the onion thinly.

Add the seasonings (sake, sugar, soy sauce, water) to a pot and heat over medium heat until boiling. Add the onion and mix. Once boiling again, add the tofu, cover, and simmer on low heat for 3 minutes. Add the snow peas and mix, then simmer for another minute.