It's strange how few Indian vegetarian restaurants there are.

You'd think that a city like Glasgow with such a developed Indian food scene would have closed this gap long ago, especially when it's an offering that's so obviously right for the city. Yes, of course you can choose vegetarian in any Indian restaurant, even if your choice is thus reduced by two-thirds, but who, vegetarian or veg-eating omnivore, wouldn't prefer a heart and soul veggie operation?

This isn't about ticking the vegetarian option box, it's a question of specialisation, of understanding Indian regional cuisines and techniques that major on vegetables and legumes. In India, the binary restaurant classification is veg or non-veg, with the latter being the majority option in many states. In Glasgow it's been meat/fish, with a purely vegetarian option treated as a minority activity.

What's also remarkable is how slow all restaurateurs (both Indian and otherwise), have been to respond fully to food intolerances and diet-related allergies. An unprecedented number of people now avoid gluten. A growing army of people now place themselves somewhere on the spectrum that spans Irritable Bowel Syndrome, Crohn's and Coeliac disease. Is this some population-wide gut reaction to industrial processed food? I'd wager that it is, but the fact of the matter is that a hell of a lot of people scan a menu these days eliminating dishes on intolerance grounds. Most restaurants respond in a piecemeal way. When you phone to book a posh restaurant, you'll likely be asked whether there's anything you can't eat. "How long have you got?" may soon be the reply as people reel off the ticking timebombs in their diet. That's before you meet the awkward squad, like me. My won't eat list includes factory farmed chicken, farmed salmon, crap industrial bread, margarine (shudder), GM cooking oil, soya, and assorted muck off a truck from those vans that drive around supplying the catering trade's equivalent of ready meals.

So there's a wonderful celebratory feeling of liberation when you walk into Usha's, with its full and varied vegetarian menu and helpful symbols denoting whether dishes are vegan (no ghee or yogurt, for instance) and gluten-free. And the selection is rich enough that meat-eaters won't be bored because it strays down paths less trodden. So alongside a number of different pakoras and samosas, you can choose sev puri, chat, delightful lentil kachoris, fragrant with roughly crushed coriander seed, and velvety potato vada mixed with softly sweated onions and chilli.

A whole posse of dishes fit into the fermented rice and pulses category, everything from chickpea-yellow dhokla crusted with fresh curry leaves, through idlis and uttapams to various dosas with sambhar and coconut chutney. The batter in our roasted vegetable dosa was arguably just a little too thick, but that beguiling fermented sourness came through brilliantly. I have eaten many with crispier edges, but few with such a good, deep flavour.

Equally, I'd be happy to ditch tandoori chicken (even made with freerange or organic bird) for Usha's tandoori paneer. The cheese could easily have been home-made, and it had been marinated in a feisty spice paste with thyme-like ajwain seeds playing a triumphant lead violin.

Seemingly simple vegetable curries testify to kitchen effort. Our okra had been gently cooked until they were almost melting, yet no way glutinous, along with caramelised onions, and floury turmeric-stained potato.

There are layers of flavour to Usha's dishes. After a bad day, I'd be consoled by its Zanzibar pilau rice, with its overlay of cinnamon and nuggets of sweet herb-wrapped coconut cream and plump raisins throughout. And by the way, if you aren't on the old gluten-free mission, the breads are all up to par.

Usha's could bump up its desserts: so far just ice cream. But there are good stand-ins in the form of lassi made with fresh fruits. Payasams, kulfi, halwa et al might come in time, I hope. Still, I wouldn't want to hack off the chef by heaping more on his/her shoulders too soon. This is a chef to cherish.