In medium-size bowl, combine yeast and warm water. Let stand 15 minutes or until surface is bubbly. Separate eggs, place whites in small bowl and set aside. With wire whisk, stir milk and egg yoks into yeast mixture until well combined. Stir in flour, butter salt and sugar; beat until smooth. Cover bowl with clean cloth; let rise in warm place until very bubbly - 1 1/2 to 2 hours. With electric mixer at high speed, beat reserved egg whites until stiff peaks form. Fold beaten egg whites into batter. Divide batter amond three small bowls. Set aside one bowl. Gently fold walnuts into mixture in one of the remaing bowls. Fold buckwheat flour and water into mixture in the other remaining bowl. To make blini, heat oven to 200F. Heat large nonstick skillet over medium heat. Add about 1/2 tablespoon oil. Spoon 1 tablespoon plain batter into skillet to form 2-inch round; continue to spoon batter by tablespoons into the skillet. Cook blini 1 1/2 to 2 minutes or until small bubbles begin to form on top. With pancake turner, turn blini over and cook 1 1/2 to 2 minutes longer, or until cooked through. Transfer to baking sheet or ovenproof serving platter and keep warm in oven until ready to serve. Repeat with remaining batter, adding more il to skillet as necessary. Divide sour cream and caviar onto blini, using about 1 scant measuring tablespoon sour cream and a scant 1/2 teaspoon caviar on each. NOTE: Caviars are available at your local supermarket or specialty food shop or by mail order from Caviarteria. To order call (800) 422-8427. Country Living/Jan/93 Posted to recipelu-digest Volume 01 Number 662 by GramWag@aol.com on Jan 31, 1998