Avial is a thick, vegetable-based dish with origins in the Kerala region. It's traditionally served at lunchtime as an essential side to rice and curry chicken or fish dishes. Avial can be found on some menus outside of India but not always made from scratch as it would be back home - you'll need to ask ahead if your Indian restaurant has this option!
Avial is essentially mashed vegetables mixed together with ground coconut meat, spiced liberally with salt and chili powder (or other spicy seasonings). There are many different varieties depending on where it comes from: for example, avials cooked by central Travancore use less water than what typical Kerala versions call for while still remaining richly flavorsome thanks to generous amounts of vegetables and spices with a thinner gravy than the Aviyal made in other parts of South India.