I was doing some research on Lambs Liver today, and came across this post from the Argalinks Cookery Doctor, Richard Maggs, which I think is a great explaination of the different types of liver and how to treat them.
Thank you Richard, great stuff. Check out the link in the title above to jump to his page.
Calves' liver is the finest - tender, juicy and rich, with lambs' liver nearly of a similar quality. Pigs' and ox liver by contrast are strong and quite tough, fine for flavouring casseroles where the flavour is diluted with other ingredients such as vegetables or mushrooms. Incidentally, take a look at the prices at your butcher's. The prices reflect the type of product: calves' liver is nearly three times as expensive as pigs' or ox liver. Finally we have poultry livers which are cheaper still, and I am a great fan of these too. They are terrific value fresh or frozen - I must buy chicken livers at least twice a month - either to turn into everyday pâté which is really easy and absolutely delicious, or to pan-fry for a quick supper by the method I give below. Sometimes, especially in the run-up to Christmas, tubs of frozen duck livers also appear so I stock up when I see them. These are best saved for luxury pâtés. Both types can also be pan-fried and then served on a plate of dressed salad with peeled grapes and a simple walnut or hazelnut oil and lemon juice dressing.
The main fact to always bear in mind is that the two different types of liver require completely different cooking techniques to render them tender and delicious. As with cheap and expensive cuts of meat, typically the rule is to cook the better cuts for a short time at a high temperature, never for too long, and to leave cheaper cuts for a long slow sojourn at a very low temperature to magically transform them.
To Prepare Liver
Carefully snip and peel away the fine membrane covering the liver. Use a sharp knife to cut the liver diagonally into thin and even slices. To ensure success and even cooking for cooking calves' and lambs' liver, it is important to always have it sliced into very even, thin strips, just under ½ an inch (9mm) thick is considered perfection. If you want, ask your butcher to do this is you are at all worried. They like to be asked. Support your local butcher and he will look after you. At the same time snip out any tough internal tubes using strong kitchen scissors.
Before cooking, some books recommend soaking liver in milk to soften the flavour. In the past, liver often had a stronger taste than it does now; modern breeding produces much milder flavoured liver, certainly calves' and lambs' liver would never need this treatment. It is a matter of personal taste with the other types. However, if in doubt, I'd suggest you also try that next time.
Cooking Calves' Liver, Lambs' Liver and Chicken Livers
Calves' and lambs' liver only need a very short cooking time to keep them meltingly tender; cook for too long and the texture changes horribly and they become progressively more and more bitter. Some chefs maintain that sprinkling with lemon juice before cooking helps prevent this, but I think it is better to learn how to cook them for the correct length of time, as below. Lemon juice can also be applied afterwards to liver that has turned bitter, but it is rather a case of shutting the stable door... I'm not really convinced it does anything but confuse the palate away from some of the bitterness frankly. Chicken livers require the same cooking techniques as calves' and lambs' liver, but cook even more quickly. Most authorities recommend serving them quite pink but it is a matter of taste.
Dust lightly in seasoned flour then sauté very lightly in butter starting with the pan over quite a high heat. On the Aga I would start off on the Boiling Plate, add the liver and then transfer to the Simmering Plate or more probably to the floor of the Roasting Oven. All it needs is for it to be sealed to keep the juices in, then cooked gently, but not for too long. A couple of minutes on either side should be enough to cook it yet still keep the middle a juicy pink. I usually find that after 2 minutes when I check, the blood is starting to bubble through on the top showing that it is time to turn it. Leave to rest on a warmed plate and deglaze the pan with some wine and/or stock etc. A spoonful of redcurrant, rowan, sloe, crabapple, plum or quince jelly/jam may be used here to good effect if you any to hand. Stick to one, though; always keep flavours focused, never confused. Boil up to make a sauce, add a little cream if you like (I don't think it works as well personally), season and then serve with a little of the sauce coating the liver.
Before you cook your liver however I would suggest you get everything else apart from any green vegetables on to cook first. I would sauté lots of thinly sliced sweet onions in some butter and a little oil right at the start, transfer the pan to the Simmering Oven for 30 minutes to soften, then return to the Simmering Plate to drive off excess water. These will keep hot, covered, in the Simmering Oven until ready to serve. I prefer them soft and light golden like this, if you prefer darker onions, now stir constantly on the top of the cooker until they are how you like them. Your patience and thoroughness will be rewarded with a really delicious flavour, rather than resorting to adding some sugar and having a sweet mixture as is sometimes suggested. These will again keep hot in the Simmering Oven. Have the other parts of the meal already cooked or prepared ready to cook so that once it is ready the liver doesn't overcook waiting for you. I would perhaps have creamy mashed potatoes cooked and then keeping hot in the Simmering Oven with perhaps another root vegetable, and then only have to fast boil say some prepared broccoli on the Boiling Plate as soon as I transfer the liver to the oven to finish cooking. Boil the kettle first just before you start on the liver too so that the vegetable water jumps to attention when you need it. This way everything will be served in perfect condition and it will be really easy to do.
Since these types of liver are quite rich, remember to keep the accompaniments simple and some kind of piquant ingredient is a good idea. I like streaky bacon that has been placed on Bake-O-Glide on a baking sheet on the floor of the Aga Roasting Oven. Here is frizzes up to a delectable crispness. Apple rings sautéed in a little butter then flambéed with a slug of Calvados also elevate proceedings if you are cooking à deux for someone special (remember to check that they like liver first or your romantic evening could go horribly wrong!). Used judiciously, balsamic vinegar is also a good foil to experiment with.
Cooking Pigs' and Ox Liver
Pigs' and ox liver as I have said, require the reverse to the above technique. No high temperatures, just long, slow cooking for several hours at the merest blip of a simmer. Executed well, and this is easy of course in the Aga Simmering Oven, these types of liver can also be transformed into delicious, nourishing and cheap casseroles, but they are pretty horrible pan-fried on their own.
Aga Cookery Doctor's Easy Slow-braised Liver
Once you have mastered the other types listed above, please do give this recipe a try. It really works very well and has surprised quite a few people over the years. It started out life as one from the brilliant Stella Atterbury's (the famous doyenne of slow cookery, who had an Aga herself, on which of course she developed many of her brilliant slow cooking techniques). It has now evolved over the years (Jocasta Innes' variation on it with orange is a winner too) and it is quite forgiving and flexible. The conclusion I have come to is that the only thing which it is a mistake to cut down on is the bacon in and on the top. Pears or quinces make delicious variations at this time of year in place of the apple.
8 oz (225g) pig or ox liver
6 tbsp stock (made from Marigold vegetable bouillon powder is fine)
salt and freshly milled black pepper
4 oz (100g) rindless smoked bacon pieces or similar
1 medium onion, very finely sliced
½ clove of garlic, finely crushed
1 medium Bramley apple
1 oz (25g) demerara sugar
¼ pt (150ml) fresh breadcrumbs
2 oz (50g) rindless streaky bacon, thinly sliced
Prepare the liver as above, cut into slices and soak in milk for at least 2 hours. Drain and pat dry with kitchen paper. Lay the strips in a small greased baking dish. Add the liquid and season. Place the bacon pieces in a dry, heavy pan and place on the Simmering Plate. Once the fat starts to run, transfer to the floor of the Roasting Oven to crispen the pieces. Alternatively this may be done on the Boiling Plate, but it will need constant stirring. Add the onion and cook, covered, for 3 minutes on the Simmering Plate. Transfer to the Simmering Oven for 30 minutes. Return to the Simmering Plate, uncover, and add the apple, breadcrumbs and sugar. Pat the stuffing over the liver, covering it completely. Lay the streaky bacon over the top, with each rasher overlapping slightly. The aim is to seal in the liquid as much as possible. If in doubt, wrap in foil.
2, 3 and 4 oven Aga: Place the baking dish on the grid shelf on the floor of the Roasting Oven for no longer than 8 minutes to get it hot. Transfer to the Simmering Oven for 2-3 hours. If necessary, moisten with a little extra stock before serving (not usually necessary).
I like to serve this with whole onions baked in foil, drizzled with a little olive oil, slow braised red cabbage and plain steamed old potatoes with a little butter and freshly chopped parsley.