Name: Hairy Bikers Slow Cooker Liver and Onions Recipe
Prep time: 15 min
Cook time: 5 h
Total time: 5 h 15 min
Ingredients: 450g lamb's liver, sliced (thawed if frozen); 2 large onions, thinly sliced; 20g butter; 1 tsp sunflower oil; 2 cloves garlic, minced; 500ml beef stock (made with 1 stock cube); 4 tsp plain flour; 1 tbsp Worcestershire sauce; 1 tsp dried thyme; Flaked sea salt and freshly ground black pepper; 200ml whole milk (for soaking)

This tender slow cooker liver and onions is made with lamb’s liver, sweet onions, butter, beef stock and thyme. The slow cooker turns everything into a rich, thick gravy with meltingly soft liver. Serves 4 in about 5 hours.

I make this on cold weeknights when I want something warming but hands-off. It fills the kitchen with the best smell while the slow cooker does all the work.

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Slow Cooker Liver and Onions Ingredients

450g lamb’s liver, sliced (thawed if frozen)
2 large onions, thinly sliced
20g butter
1 tsp sunflower oil
2 cloves garlic, minced
500ml beef stock (made with 1 stock cube)
4 tsp plain flour
1 tbsp Worcestershire sauce
1 tsp dried thyme
Flaked sea salt and freshly ground black pepper
200ml whole milk (for soaking)

Slow cooker liver and onions in rich gravy served with mashed potatoes — Slow cooker liver and onions in rich onion gravy

How to Make Slow Cooker Liver and Onions

Soak the liver: Place the liver slices in a shallow dish and pour over the milk. Leave for 30–60 minutes, then drain and pat dry with kitchen paper. This removes the metallic taste and gives a milder flavour.
Coat in flour: Mix the plain flour with salt and pepper in a shallow dish. Lightly coat each liver slice in the seasoned flour, shaking off the excess.
Brown the liver: Heat the butter and oil in a large frying pan over medium-high heat. Brown the floured liver for 1–2 minutes on each side until golden but not cooked through. Set aside.
Soften the onions: In the same pan, add the sliced onions and garlic. Cook for about 5 minutes until soft and starting to turn golden. Transfer to the bottom of your slow cooker.
Layer in the slow cooker: Place the browned liver on top of the onions. Pour the beef stock over everything, then add the Worcestershire sauce and dried thyme. Stir gently.
Slow cook: Cover and cook on LOW for 4–5 hours or HIGH for 2–3 hours. The liver should be very tender and the sauce thickened into a rich gravy.
Season and serve: Taste and adjust seasoning with salt and pepper. Serve hot with creamy mashed potatoes and greens.

What Are the Best Tips for Slow Cooker Liver and Onions?

Soak in milk first: Soaking the liver in milk for 30–60 minutes draws out the strong, metallic taste. This is the single best thing you can do for a milder flavour. Do not skip this step.
Choose lamb’s or calf’s liver: These are the most tender with the mildest flavour. Beef liver works but has a much stronger taste and firmer texture.
Always brown the liver first: Coating the liver in seasoned plain flour and browning it before slow cooking builds a flavourful crust. The flour also thickens the gravy as it cooks.
Thicken the gravy further: If you want an even thicker sauce, mix 1 tbsp cornflour with 2 tbsp cold water. Stir this into the slow cooker during the last 30 minutes on HIGH.
Add bacon for extra flavour: Chop 2–4 rashers of bacon and fry until crisp before cooking the onions. Add the bacon and rendered fat to the slow cooker. For the classic stovetop version with bacon, try our liver and bacon recipe.

What Goes Well with Liver and Onions?

Creamy mashed potatoes are the classic choice here. The gravy soaks into the mash beautifully. For something richer, serve with dauphinoise potatoes instead.

Steamed greens work well on the side. Cabbage, kale, green beans or peas all pair nicely. A slice of crusty bread is also good for mopping up the last of the gravy.

For a full comfort food spread, start with a bowl of leek and potato soup before the main course.

Slow cooker liver and onions with rich onion gravy — Tender liver and onions with thick onion gravy

How Should You Store Leftover Liver and Onions?

Store leftovers in an airtight container in the fridge for up to 2 days. Liver can become slightly firmer when reheated, so keep this in mind.

Reheat gently in a saucepan over low heat with a splash of beef stock to loosen the gravy. Avoid the microwave if possible, as it tends to make the liver rubbery.

You can also freeze this dish for up to 3 months. Let it cool completely, then transfer to a freezer-safe container. Thaw overnight in the fridge and reheat on the hob until piping hot.

Nutrition Facts

Calories: ~370 kcal
Protein: 38g
Carbohydrates: 18g
Fat: 15g
Iron: ~15mg
Dietary Fibre: 2g

Slow cooker liver and onions served with mash and greens — Liver and onions with mashed potatoes and steamed greens

Frequently Asked Questions

How long do you cook liver and onions in a slow cooker? Cook on LOW for 4–5 hours or HIGH for 2–3 hours. The liver should be very tender and the gravy thick when ready.

How does this compare to the classic Hairy Bikers stovetop version? The original Hairy Bikers recipe is a quick stovetop liver and bacon with onion gravy that takes about 15 minutes. This slow cooker version is hands-off and produces a more tender result over 4–5 hours.

Why is my slow cooker liver tough or chewy? The most common cause is overcooking, so avoid going beyond 5 hours on low. Soaking in milk for 30–60 minutes beforehand also helps keep it tender.

Can I add other vegetables to slow cooker liver and onions? Yes, sliced mushrooms and carrots work well. Add them with the onions at the start for a heartier one-pot meal.

Can I prepare this ahead of time? You can brown the liver and soften the onions the night before. Store in the fridge, then assemble in the slow cooker and start cooking the next morning.