Prep the liver: Pat the slices dry with paper towels.
If desired, soak in milk or buttermilk for 20–30 minutes to mellow the flavor, then drain and pat completely dry. Trim any tough membranes along the edges.
Season the dredge: In a shallow dish, mix flour, 1 teaspoon salt, pepper, paprika, and garlic powder. This adds flavor and helps the crust crisp up.
Caramelize the onions: Heat a large skillet over medium heat.
Add 1 tablespoon oil and 1 tablespoon butter. Add the onions and a pinch of salt. Cook, stirring occasionally, for 12–15 minutes until soft, golden, and lightly caramelized.
If they brown too fast, lower the heat. Transfer onions to a plate and keep warm.
Heat the pan for frying: Wipe the skillet if needed. Add 2 tablespoons oil and 2 tablespoons butter.
Heat over medium-high until the butter foams and subsides. You want the pan hot so the flour crisps on contact.
Dredge the liver: Working in batches, coat each slice lightly in the seasoned flour. Shake off excess.
A thin coat is key for a crisp, not gummy, crust.
Pan-fry quickly: Lay the liver slices in the hot pan without crowding. Cook 1.5 to 2 minutes per side for calf’s liver (slightly longer for beef liver), until browned with a faint blush in the center. Do not overcook—it turns grainy and tough fast.
Season and finish: Return onions to the skillet to warm through. Splash in Worcestershire if using, and toss gently.
Off the heat, squeeze a bit of lemon or add a dash of vinegar to brighten.
Serve right away: Top the liver with the onions, sprinkle with parsley, and serve hot. Great with mashed potatoes, steamed green beans, or buttered rice.