Tonjiru is usually made by stewing thinly sliced pieces of pork, alongside vegetables, in dashi stock, and flavoured by dissolving miso.

[2] Common additional ingredients include burdock root, konjac, seaweed, spring onions, daikon radish, carrot, tofu including fried tofu (aburaage), tubers such as potatoes, taro or sweet potato, and mushrooms such as shiitake and shimeji.

[2] On rare occasions, mildly degreased (not crispy) bacon can be used in place of pork.

The Japanese character for pig (豚) can be pronounced either as buta (the kun'yomi way), or as ton (the on'yomi way).

A version of the dish, containing sweet potatoes, as served to skiers in the ski resorts of Niigata Prefecture up until about 1960, is known as sukii-jiru ("skiing-soup").