In a 12 to 14 inch saute pan, heat oil until smoking. Dredge the chicken livers into the seasoned flour and shake excess flour off. Saute chicken livers until crisp and golden brown, about 8 to 10 minutes, and remove to plate. Add leeks and apricots to pan and cook until leeks are softened, about 8 to 10 minutes. Add chicken livers back to pan, add vinegar and butter and cook until liquid is reduced by half. Add endive to pan. Toss to coat and serve immediately.