Abd al-Rahman bin Ghanm al-Ash'ari says: I asked Sayyiduna Mu'adh (may Allah be pleased with him): Did you perform ablution after (eating) something cooked on fire? He replied: Yes! When one of us ate something cooked on fire, he would wash his hands and mouth, and we counted that as ablution.
Al-Bazzar recorded it, and it is a narration of al-Hasan bin Yahya al-Khushani, who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1299