tsuけるkerutsuけるkeru
1.

To place an object into a liquid so that it becomes immersed or covered.

2.

To submerge food items in a seasoned mixture, such as salt or fermentation agents, for preservation or flavor enhancement.

3.

To temporarily lower an item into a liquid, allowing it to absorb some of that liquid's properties or characteristics.

Example:

彼はスプーンをスープの中につけた。