Pat the chicken livers dry with paper towels. Toss them lightly in flour mixed with chicken spice (if using) until evenly coated. Shake off any excess flour—this will help them crisp up nicely in the pan.

Heat 2 tablespoons of oil in a large skillet over medium-high heat. Once hot, carefully place the livers in a single layer, cooking for about 3 minutes per side until they’re browned but still tender inside. Remove the livers and set them aside on a plate.

In the same skillet, add the remaining oil and sliced onions. Cook over medium heat, stirring occasionally, until the onions turn golden brown and caramelized, about 6–8 minutes. Lower the heat if needed to prevent burning.

Sprinkle 1 tablespoon of flour into the skillet with the onions, stirring to combine for about a minute. Slowly add the beef stock, stirring to deglaze the pan and combine all flavors. Add the tomato sauce, stir, and let the gravy simmer for 2–3 minutes, thickening slightly. Season with salt and black pepper to taste.

Return the cooked livers to the skillet, stirring gently to coat them in the gravy. Let everything heat together for another 2 minutes, allowing the flavors to blend. Serve hot, topped with extra gravy.