Prepare the Ingredients: Start by blending the canned tomatoes in a blender until smooth. This will serve as the base for your rich and creamy sauce. Next, drain the beef liver, cut it into small, even-sized pieces, and pat it dry with paper towels. Drying the liver is key to achieving that golden caramelization.
Sear the Liver: Heat 1 tablespoon of butter in a large, non-stick frying pan over medium-high heat. Add half the liver pieces and cook for 3-4 minutes, turning frequently, until caramelized on all sides. Transfer the cooked liver to a bowl, season with salt, and repeat the process with another tablespoon of butter and the remaining liver. Don’t worry if the liver isn’t fully cooked at this stage; it will finish cooking later. Cooking in batches is crucial to achieving a proper sear without overcrowding the pan.
Caramelize the Onion and Garlic: Reduce the heat to medium and melt the remaining tablespoon of butter in the pan. Add the diced onion and cook for 10-11 minutes, stirring occasionally, until softened and golden. Add the chopped garlic and cook for an additional 1-2 minutes, stirring continuously to prevent burning as the onion starts to caramelize.
Create the Tomato Cream Sauce: Pour the blended tomato mixture into the pan with the caramelized onions and garlic. Stir well to combine and bring the mixture to a gentle simmer over medium heat. Allow the sauce to reduce for 12-15 minutes, stirring occasionally, until it thickens.
Combine and Cook: Return the seared liver (and any juices from the bowl) to the pan. Stir to coat the liver in the sauce, then simmer for 4-5 minutes. Add the full-fat cream and soured cream, stirring to combine. Generously season with sea salt and freshly ground pepper to taste.
Optional Baking Step: For an extra layer of flavor, transfer the mixture to a glass casserole dish and bake at 400°F for 10 minutes. Alternatively, skip this step and continue cooking the dish in the pan for another 4-5 minutes.
Garnish and Serve: Serve the Beef Liver with Tomato Cream Sauce hot, garnished with fresh thyme leaves if desired. This dish pairs beautifully with roasted vegetables, cauliflower rice, or a simple green salad.