soot on the bottom of a pot or pan
Refers specifically to the black soot that accumulates on the outside bottom of cooking pots and pans, especially from open flames or gas stoves.
Soot stuck to the bottom of the pot we used while camping.
鍋墨を落とす専用の洗剤がある。
There is a special detergent for removing pot soot.
Compound of 鍋 (なべ, 'pot') and 墨 (すみ, 'ink'), referring to the ink-like black soot on pots.