What is Vegan Friendly?
A lot of Indian cuisine is already vegan (does not contain meat, eggs, or dairy products). The chances are that your restaurant, or cafe already has enough vegan items in the menu, where a person who takes a vegan diet, can have a complete meal there.
By displaying a "vegan friendly" sign to your patrons and in your marketing material, you get to tap into a growing market segment without having to make any alterations to your menu.
The only change you would have to do, is to put up a poster in your kitchen for your staff, so that they know which items are vegan, and don't end up adding any dairy products in a dish that doesn't necessitate adding dairy ingredients (for example: pulao, channa masala).