At Sultan's Kitchen, open since 1981, chef/owner Özcan Ozan serves some of the most deeply flavored food to be tasted in downtown Boston. The place is small but welcoming, with an open kitchen and a few tables for eating in. The concentration of office buildings in the area make lunchtime business brisk - people stream through the door for Ozan's shish kebabs and pita sandwiches, as well as the hummus, tabouli, baba ganoush and falafel. The kebabs here are tender and flavorful - choose from variations of lamb, chicken, swordfish or beef. Rather than occupying the fringes of the quick lunchtime meal, vegetables such as okra, eggplant, green beans, artichokes and even onions can be the meal at Sultan's Kitchen. Many are braised with shallots, carrots, herbs and olive oil, a method that fills them with the rich, filling and savory qualities of a main course. The sampler plate of six vegetable and legume dishes reveals just how satisfying a plate of veggies can be. A fridge is stocked with containers of hummus, baba ganoush and other dishes that patrons can easily pick up on the way home from work.