common gravy options:
Dhal (chickpea/lentil based gravy), Curry sauce, Rasam (tamarind juiced based sauce), yogurt
Banana leaf rice sets come with a wide variety of vegetables, it differs from day to day and restaurant to restaurant. Popular veggies are spinach, potatoes, raw cucumber and onions etc. This makes banana leaf rice a great vegetarian dish. Of course, any Indian restaurant has a variety of fried meats that can be added to the set.
It is also common to add Papadum - a thin, crisp Indian cracker.
Banana Leaf Rice is traditionally eaten by using your (right) hand instead of cutleries and served on a banana leaf (hence the name).