温める
あたためる · atatameru · JLPT N3 · verb-ichidan
to warm
🔥🍲 温 = warm; atataKAI (warm) becomes atataMERU (to make warm)
The kanji 温 means warm, as in 温泉 onsen (hot spring). Learn it as a pair with the adjective 温かい atatakai, warm: swap -kai for -meru and you get the verb, to make something warm. Say it aloud: a-ta-ta, a little stutter of heat.