Melt oil n heavy large skillet over medium heat. Add cabbage and onion and saute until tinged with brown, about 12 minutes. Transfer cabbage mixture to medium bowl. Mix in rice, feta cheese and 3 tablespoons dill.
Lay 1 wonton wrapper on work surface. Brush entire surface of wrapper with egg white. Press 1 generous tablespoon filling in center of wrapper.
Fold over dough, pressing opposite corners together to form triangle. Seal edges, pressing out air around filling. Repeat process with remaining wonton wrappers, egg white and filling.
Boil ravioli in large pot of boilingsalted water until dough is tender, about 8 minutes. Drain. Transfer ravioli to large bowl. Toss with 1/2 cup yogurt. Garnish with remaining dill and serve, passing remaining yogurt separately.