Prep the liver: Rinse and pat dry.
Soak slices in milk or water for 20–30 minutes to mellow the flavor. Drain and pat very dry.
Season and (optionally) dust: Sprinkle with salt, pepper, and paprika. If you like a light crust, dust with a thin coating of flour.
Cook the onions: Heat butter and 1/2 tablespoon oil in a skillet over medium heat.
Add onions and a pinch of salt. Cook 8–10 minutes, stirring, until soft and golden. Add garlic in the last minute.
Transfer onions to a plate.
Sear the liver: Add remaining oil to the same pan. Increase heat to medium-high. Add liver slices in a single layer without crowding.
Sear 1–2 minutes per side until browned on the outside and just slightly pink inside.
Combine and finish: Return onions to the pan. Toss for 30 seconds to coat and warm through. Taste and adjust seasoning.
Garnish with parsley or scallions.
Serve: Great with mashed potatoes, rice, or crusty bread, plus a squeeze of lemon if you like brightness.
Prep and soak: Soak sliced liver in cold water for 10–15 minutes. Drain and pat completely dry.
Mix the sauce: In a small bowl, combine soy sauce, oyster sauce (or sugar), vinegar, and black pepper. Stir in cornstarch slurry if using.
Stir-fry aromatics: Heat oil in a wok or large skillet over high heat.
Add onion, garlic, and ginger. Stir-fry 1–2 minutes until fragrant.
Cook the liver fast: Add liver in a single layer. Sear 60–90 seconds, flip, and cook another 60 seconds.
It should be just cooked through but still tender.
Sauce it up: Pour in the sauce. Toss 30–45 seconds until glossy and lightly thickened. Add bell pepper near the end if you want a slight crunch.
Finish and serve: Top with scallions.
Serve with steamed rice and a side of cucumbers or sautéed greens.