This is the 2693rd most frequent Japanese word.
煮込み
Simmered dish.
In this sentence, 煮込み (nikomi) is used as a verb meaning 'to stew or simmer'.
これを弱火で煮込みながら、他の料理を作りましょう。
Let's cook this over low heat while preparing other dishes.
Here, 煮込み (nikomi) is part of the compound noun 煮込み料理 (nikomi ryouri), which refers to the category of stewed dishes, emphasizing the preparation style.
彼女は夜ご飯のために長時間の煮込み料理を準備しています。
She is preparing a long-simmering stew for dinner.
Here, 煮込み (nikomi) is a noun referring to a stewed dish made by simmering ingredients together.