niru
1.

To cook food by immersing it in a liquid and applying heat, resulting in a soft or tender texture, often with added flavoring.

2.

To prepare a dish by slowly heating ingredients in a seasoned broth or water until they are fully cooked and palatable.

3.

To transform solid food items into a soft consistency through the process of boiling or simmering in flavored liquid.

Example:

くたくたに煮る。