As Russian-American von Bremzen and British writer Welchman remind us in their introduction, the food traditions of an ""empire"" that covers one sixth of the globe and encompasses over a hundred nationalities and languages have got to extend beyond borsch and blini. Indeed, the body of their cookbook--put together from family recipes, library research, and extensive travel and tasting--confirms not only a wide variety of dishes but also an interesting repertoire of distinctive flavors. One problem is the unavailability here of common, signature ingredients--but, just as the new Russian immigrants are devising substitutes, these authors suggest tamarind paste as a stand-in for the prized sour plums that sauce the Georgian stew back home; a white wine of your choice for the Moldavian wine used in a popular cod and red-pepper dish; or a Tatar wedding pie, made with layers of ground beef, rice, chopped egg and raisins, that simply eliminates the native kort, described as a sweet, dry cottage cheese. Fortunately, wild mushrooms, smoked salmon, and other special essentials can be had here, as can everything you need for the pumpkin fritters, aromatic pilafs, and a host of other piquant and interesting dishes. And the hearty, zesty fare that's featured at the von Bremzen/Welchman table is right in step with current inclinations.