The spice route now threads through Commack. Here, the seasoned Kiran Palace group opens its third restaurant; the modest spot gives off sparks. The other branches are in Hicksville, Long Island's capital of Indian cooking; and in Selden, one of its outposts. The latest takes over the shopping-center storefront of Tian Tian, a dreary Chinese eatery, and turns it into a little destination. And if you want more than a quick curry before, during or after Oscar's Sunday party for "Slumdog Millionaire," Kiran Palace is among the tasteful nominees..