Rinse Liver using cold water; place in a medium bowl. Completely cover with milk. Cover and refrigerate 30 minutes.
2. Heat a large nonstick skillet over medium-high heat until hot. Add onions; cook and stir 15 to 20 minutes until soft and caramelized, reducing heat, if necessary. Remove onions from skillet; set aside and keep warm.
3. Remove liver from milk; discard milk. Combine flour, salt and pepper in a small bowl. Using a sifter, evenly dust each piece of liver with seasoned flour mixture. Melt 1-1/2 teaspoons oil and 1-1/2 teaspoons butter in the same skillet until hot. Add half of the liver; cook 3 to 4 minutes on each side until evenly browned on outside, but pink inside. Repeat with remaining 1-1/2 teaspoons oil, 1-1/2 teaspoons butter and remaining liver.
Cook's Tip: For glazed onions, remove the liver from skillet after cooking; set aside and keep warm. Return caramelized onions to the same skillet with 1/4 cup water; deglaze the pan. Stir and cook until water is almost completely evaporated.