In the four years since it opened, ramen chain Soranoiro has garnered widespread praise — and for good reason. In addition to its standard shoyu and shiō-based ramen, it also offers more adventurous concoctions including ramen with sudachi (Japanese citrus), umi-budō (sea grapes) or, unbelievably, white chocolate.

But I've come to the Tokyo Station branch for another reason: vegan ramen. A bright poster on the restaurant's wall touts the benefits of various vegetables used in the soup, and displays a mouthwatering image of the dish, the bowl stacked to the brim with renkon (lotus root), broccoli and cabbage in a bright orange carrot soup.

Owner Chihiro Miyazaki opened the first Soranoiro in Tokyo's Kojimachi neighborhood in 2011. His original vegetable noodle dish was packed with fresh vegetables but also contained seafood, butter and a meat topping — the vegan version didn't appear until March, 2014.