Prepare the liver: Rinse the 2 lbs sliced turkey liver under cold water to clean it. In a large bowl, soak the liver in 1 1/2 cups milk while you prepare the onions. This step is crucial for tenderizing the liver and removing any bitter taste.
Sauté the onions: In a large skillet, melt 2 tablespoons butter over medium heat. Add the 2 large sliced Vidalia onions to the skillet, sautéing them until they become golden brown and caramelized, about 10-15 minutes. Season with a pinch of salt to enhance the sweetness. Once caramelized, remove them from the skillet and set aside.
Prepare the flour mixture: In a shallow dish, combine 2 cups all-purpose flour with salt and pepper to taste, mixing well.
Coat the liver: After soaking, drain the liver slices and pat them dry with paper towels. Dredge each slice in the seasoned flour mixture, ensuring an even coating.
Cook the liver: In the same skillet, add the remaining 2 tablespoons of butter. Heat over medium-high heat until bubbly. Place the floured liver slices in the skillet, cooking for about 3-4 minutes on each side, or until nicely browned. Ensure not to overcrowd the skillet; cook in batches if necessary.
Add onions: Once the liver is browned, return the caramelized onions to the skillet. Stir gently to combine, and lower the heat to simmer. Let everything cook together for an additional 5-7 minutes, until the liver is cooked through and slightly tender. A good cue is when the liver feels firm yet springy to the touch.