Musnad Ahmad 1153:572

Haywah ibn Shurayh narrated to us, he said: Baqiyyah narrated to us, he said: Buhayr ibn Sa’d narrated to me, from Khalid ibn Ma’dan, from Abu Ziyad Khiyar ibn Salamah, that he asked Aisha about onions. She said: "Indeed, the last food the Messenger of Allah, peace and blessings of Allah be upon him, ate was food containing onions."