dissolve yeast and sugar in 1/2 c of warm water. cover lightly with a damp cloth and leave in a warm place for about 20 minutes, or until mixture begins to foam.
warm a large mixing bowl by rinsing with hot water and drying thoroughly. sift flour into warmed bowl. make a depression in the center, pour in yeast mixture, and beat into flour. continue beating, gradually adding the remaining warm water until mixture is the consistency of pancake batter. cover mixture with a damp cloth and leave in a warm place for 1 hour, or until bubbly.
in a small bowl , prepare filling by mixing walnuts , sugar, and cinnamon. set aside.
preheat oven to 375.
place vegetable oil in a heavy skillet and swirl to coat evenly. heat pan over high heat.
pour about 1/4 c batter into heated pan. tilt pan gently to even out batter, but keep pancake fairly thick and round. cook until it begins to bubble and comes awy easily from pan. cook only one side of pancake.
use a spatula to remove pancake from pan and place panckae on a greased cookie sheet or baking pan. put 2 tbsp of walnut filling on uncooked side of panckae and fold in half. firmly pinch edges together to keep filling in place.
repeat with remaining batter and filling, adding oil to pan as needed
when all pancakes are filled, place cookie sheet or baking pan in oven and bake for 10 to 15 minutes. remove from oven and cool slightly. dip pancakes in syrup or serve with cottage cheese our sour cream.