Dunhinda
Dunhinda is really far (in Attidiya, between Dehiwala and Ratmalana) and basically hidden in a carefully constructed jungle. It is, however, definitely worth a trip. Dunhinda has perhaps the best rice and curry in Colombo and it is veg for deep cultural reasons, not as a fad.
Dunhinda is old school Sinhala food, rice and curry, kola kanda, they even do a great kavum. While you can catch the kola kanda truck roaming around sometimes, nothing beats their roadside location for a good veg meal.
Amro Vegetarian Cafe
Amro Vegetarian Cafe is a family restaurant with charming staff and a cozy atmosphere. They serve up some authentic Sri Lankan dishes; from rice and curry to an extensive selection of smoothies and juices, expect to find many healthy options. The four aunties that run Amro care about their customers and are happy to accommodate any wishes and needs. If you are looking to learn more about the local cuisine without eating meat, try some of their delicious dishes.
Shanmugas
With a restaurant in Dehiwela and a smaller takeaway outlet at the Crescat shopping centre, Shanmugas is not only Colombo's oldest vegetarian restaurant, it is also one of the best. Their menu is huge with firm favourites such as the paper masala dosai that shiny cone of deliciousness comes with a sambar and two chutneys. There is all your classic Indian favourites such as idli, pani puri and chillie parota. Order a North or South Indian Thali if you want to try a bit of everything.
They also have rice and noodle dishes (such as the vegetable nasi goreng) for those that aren't keen on something curry-based. Shanmugas has a wealth of extra services. Their "Pick and Go" service is very popular, call in your order and it will be ready for when you get there, perfect for those hungry vegetarians on the run. Prices are moderate but serving sizes are pretty large so you don't need to order a lot to feel satisfied.
Mathura
Mathura is considered one of the best South Indian restaurants in the city and offers a comfortable setting as well as sumptuous dishes. From the crispy masala dosai to the filling potato curry, Mathura serves traditional meals with authentic flavors. It specializes in dosa, flat breads, rice and vegetable preparations served with sambar, chutney and all kinds of mouthwatering sauces.
Milk and Honey
For a more modern take on veg, Milk and Honey Cafe on Barnes Place cannot be beat. This old colonial house does great veg and vegan bites and cakes. They also have a great range of fruit and veg juices. There is also a kids store with books and toys attached.
Shri Vihar
Shri Vihar is situated in the heart of Colombo and provides traditional Indian cuisine at reasonable prices. Offering both Northern and Southern dishes, this place will satisfy many different tastes. Its extensive menu includes numerous dishes, sweets, snacks, desserts and juices. Shri Vihar’s skillful chefs carefully prepare spicy and creamy dishes.