On the left bank near Notre-Dame in the heart of tourist territory, just round the corner from a whole batch of these awful restaurants with waiters outside trying to entice you in, you will find La fourmi ailĂ©e– the flying ant (8 rue du fouarre 75005), which is an entirely different proposition.
It has been refurbished recently, and I am not so keen on the new decor (changed from looking like a cosy old library to a more modern  diner style), but everything else is as good as it has always been. The clientele are still mainly students and canny tourists.
The food is fresh and plentiful, and shock horror for Paris, the staff are friendly. Very suitable for taking your Vegetarian friends.
It is also a Salon de thé, providing you with a good venue for relaxing over tea and pâtisseries.