If I am around Bugis, I would definitely go to Fortune Centre which housed many vegetarian eateries! I love the Vegetarian Nasi Lemak (coconut rice), Vegetarian Otah and assorted Organic Buns sold by Xin Yuan Vegetarian Food Trading.
You can also get your supply of Veg*n Stuff (mock meat, canned food, vegetarian cooking/chilli sauces, ready-to-serve food, tibits/cracker, instant noodle, belacan, Bak Kut Teh sachet, Funori etc)
For Tourist, this is a convenient location to get there in town (nearby MRT: Bugis) The Vegetarian Bak Kwa (BBQ Pork/Pork Jerky) is available in this shop. I remember my ex-colleague from Hong Kong was tasked to buy this Bak Kwa (non-vegetarian) whenever he was in Singapore for business trip. Here you can find the veg*n version! Besides Bak Kwa (BBQ Pork), Veg*n Meat Floss is available there too.