1mediumyellow onionthinly sliced, slices separated into rings
Arrange the liver slices on a cutting board or on a couple of large plates. Blot them dry with paper towels. Sprinkle them with salt, black pepper, garlic powder, and smoked paprika.
Heat 1 tablespoon of olive oil in a large (12-inch) nonstick skillet over medium-high heat. Add the onions. Cook, stirring often, until golden-brown, about 7 minutes. If the pan gets too hot, lower the heat to medium.
Remove the onions from the skillet with a slotted spoon. Place them on a plate and cover with foil to keep warm.
Carefully wipe the skillet clean with paper towels (it will be hot). Add the remaining tablespoon of olive oil and lower the heat to medium. Add the liver slices, in two batches if needed.
Cook the livers briefly, about 3 minutes per side. Don't overcook them or they'll become tough and grainy**. If there are a few thicker or misshapen slices or chunks, you can briefly cook them on the edges too. But first, remove the already-cooked thin slices to a plate.
Arrange the cooked livers on a serving plate, top them with the sautéed onions, and serve.
*The liver of the mature cow has a dense, gummy texture and a strong metallic flavor. A calf's liver is relatively tender and mild. If all you can find is a mature cow's liver, it's not a bad idea to soak it in milk while you prepare and cook the onions. This will help reduce the metallic taste.**I should probably point out that according to the USDA, we should cook beef internal organs to 160°F, which is well-done.