Sprinkle dry yeast over warm (110 degrees F) water.
Heat cottage cheese to lukewarm in saucepan; add sugar, onion, butter, dill, salt, baking soda, egg and yeast mixture. Add flour to form a stiff dough, beating well after each addition. Cover; let rise in a warm place, 85 degrees F to 90 degrees F, until double, 50 to 60 minutes.
Stir dough down. Turn into a well-greased 1 1/2-quart round bottom casserole. Let rise in a warm place until light, about 30 to 40 minutes.
Bake at 375 degrees F until golden brown, 40 to 45 minutes.
Brush with butter; sprinkle with kosher or sea salt.