Ayambil (Ayambil vrata) is a one-meal-a-day practice to minimize taste and attachment. The menu is intentionally plain: boiled or simple preparations, no oil/ghee, no salt in many traditions, and no milk, fruits, or fried items. Details can vary by sect and local maryada, so please check with your guru or local sangh.

Typical Ayambil menu (general Jain guidance)

• Grains (boiled/plain): rice, wheat, barley, jowar, bajra
• Pulses/daal (boiled): moong dal (green or yellow), masoor, toor, chana dal
• Light vegetables (boiled, no tempering): lauki/doodhi (bottle gourd), tori/ridge gourd, kaddu (pumpkin), tinda, parwal
• Roti/chapati: dry-roasted (without oil, ghee, or salt when your maryada allows)
• Seasoning (minimal or none): many traditions prefer no spice; some allow very limited rock salt, jeera, or black pepper
• Water: boiled or prepared as per local rules; typically consumed during the day

Items often avoided

• Salt, sugar/jaggery
• Milk and all dairy products
• Oil, ghee, butter
• Fruits and dry fruits
• Fried or highly spicy items
• Raw/green vegetables in stricter practices

Notes

• Exact offerings vary by Digambar vs. Shwetambar traditions and by local temple/sangh rules.
• Ayambil foods should be prepared fresh on the day of Ayambil if possible; precooked items from a previous day are generally not permitted.

You can read more here and a concise summary here