When I’m cooking a meal for a large group, I always start by making stock a few days beforehand. Our dinner on Thanksgiving Monday, for instance, starts with a turkey stock made on the preceding Saturday. Last year’s New Year’s Eve dinner started a couple days before when I made a ham hock broth. Stock is the flavour-foundation of the meal. The showpiece of Thanksgiving dinner is the turkey, and besides enjoying the meat, turkey-flavour finds its way into the soup, the stuffing, the gravy, and often the vegetables. The turkey stock unites the dishes.
The ideal stock has three characteristics: above all it is flavourful, with a full mouthfeel, and it should be (relatively) clear.
The old adage is that the flavour of a stock comes from meat, while the body comes from bones. This is mostly true. The bulk of the meaty flavour comes from the meat, while the body is formed by the conversion of a connective tissue called collagen into gelatin, which occurs in hot, moist environments like the stock pot. The best sources of collagen are the cartilaginous joints of young animals (veal “knuckles,” for instance, which are the knee joints, as well as necks and feet), but tough muscles are also high in useful connective tissue (lamb and beef shank, for instance).
Restaurants have the luxury of ordering in the optimal bones by the case. At home I use any and all bones and clean meat trim that I collect when cutting animals.
Roast the bones. The bones used to make stock are cooked before they are simmered. Classically they are either roasted to make a brown stock or poached to make a white stock. At home, I always roast the bones: it’s simpler and quicker than poaching, plus I like the colour and flavour of the stock that it produces. If you’re interest in making classical white stocks, read The French Laundry Cookbook.
Whether the bones are roasted or poached, it’s important that they are cooked before they are simmered. The two main reasons that stocks end up cloudy are these: one, that proteins on the surface of the meat are leached into solution; two, that fat from the meat is emulsified into the stock. Cooking the bones coagulates the surface proteins and renders excess fat in the meat, both of which will result in a clearer stock.
Roasting the bones will form a fond in the pan. This is a rich repository of flavour and should be collected and included in the stock. You can deglaze the hot pan with water, but I like to use a bit of dry cider or wine, depending on the type of stock, as the acidity will help extract the gelatin from the bones during simmering. Make sure to pour off and reserve any fat in the pan before deglazing; we don’t want any fat in our stock.
The Vegetables. You can use vegetable trim, but don’t use vegetable garbage. Carrot peelings are for the compost pile, not the stock pot.
I also roast the vegetables. Preferably this is done in the fat that is rendered from the bones and trim during the roasting process.
Ratio of Bones to Water. In culinary school we were taught that the ideal ratio was 4:2:1 water, bones, vegetables, by weight. Ruhlman suggests 3:2 water to bones in his book Ratio. I guess this is helpful, but really you’re just going to fill a pot with all of the bones that you have, then add enough water so that they’re covered. If a portion of bone isn’t covered in water, you won’t extract any of its flavour or gelatin. I’ve been measuring the amount of water it takes to cover a certain weight of bones, and I’ve found that it varies from animal to animal. Chicken bones are light and small, and it takes more water per pound of bones to cover them then, say, large dense beef knuckles.
Start cold. It’s important to chill the bones thoroughly after roasting. We want to start with cold bones in cold water, then very slowly raise the temperature of the liquid, over the course of at least an hour, to a gentle simmer. We want the the surface proteins to coagulate very slowly, so that they can form clumps that will either rise to the surface or fall to the bottom of the pot. If heated quickly the proteins will not conglomerate, and will stay suspended in the stock. Water from the cold tap is also said to taste better than that from the hot tap, which has sat in the water heater for some time.
Skim like a mother. As the temperature of the water increases, the aforementioned surface proteins will coagulate and throw foam or scum onto the surface. This happens throughout the stock-making process, but especially as the water is coming up to temperature. These impurities should be skimmed away.
Simmer very, very gently. A stock pot should never boil. The ideal temperature to hold a stock at is at a faint, faint simmer. The pot should be barely bubbling. I like to see it steaming, but not bubbling. Boiling jostles the contents and clouds the stock. Sometimes little pockets of air get trapped between bones, and as the water heats up, the air expands, escapes, and bubbles to the surface, so that the pot appears to be gently boiling when it’s really not.
Simmering time. In culinary school they made us memorize recommended simmering times for different types of stock. If I remember correctly, they were:
- vegetable broth: 45 to 60 minutes
- fish and seafood: 45 to 60 minutes
- poultry: 2 to 3 hours
- veal and beef: 6 to 8 hours
I only follow these recommendations for vegetable broth. Every other type of stock – fish and seafood, poultry, pork, lamb, veal, and beef – I leave for 24 hours. While you can make a fairly flavourful stock in only a few hours, simmering for 24 hours will maximize gelatin extraction.
Adding Vegetables and Herbs at the End. So let me ask, rhetorically: if a vegetable stock has its best flavour after only an hour of simmering, why would I add vegetables at the start of a poultry stock and let it simmer for a few hours? Why not add them only for the last hour? Even better examples of this principle are black pepper and herbs, which release their purest flavour after only fifteen minutes of simmering. If you add herbs at the beginning of a stock, by the time you’ve extracted the flavour of the meat and the gelatin of the joints, what little herb flavour remains will be muddy and muted.
I tailor the vegetable and herb content to each type of stock. For instance, with poultry stocks I like lots of celery, and a variety of herbs. For turkey stock I like sage. For beef stock I use a small amount of tomato. For lamb stock the only herb I use is thyme.
Freezing. When I make chicken stock from a couple of carcasses, there isn’t usually any need to freeze the stock, as we can easily consume it as soup over a few days. However, when making pork and beef stock using all the bones from an entire side, there is way too much stock to consume at once, so some of it has to be frozen.
Whether you’re freezing the stock or not, it’s good to chill it thoroughly before consuming, as any fat will rise and solidify on the surface, where it is easily removed. (Culinary school considered even a drop of fat in stock a terrible crime. Realistically it depends on what the stock will be used for. It’s good to have a few drops of fat shimmering on the surface of chicken noodle soup. You just don’t want it to be greasy.)
One good way to freeze the stock is in ice cube trays. Once frozen, you can pop the cubes out and store them in a Ziploc bag. This is handy because you can easily remove any amount of stock at a given time. The downside to this method is that it takes up a lot of room in the freezer. I’ll typically freeze part of a batch of stock by filling up large bags, and part in ice cube trays. When I plan on making soup and I know I’ll need a couple litres of stock, I can pull out the large bags. When I only need a couple ounces to fortify a sauce, I can pull out a few cubes.
A General Procedure for Making Stock
- vegetables, usually onion, celery, carrots, and garlic
- dry cider or wine
- cold water, enough to cover the bones, usually 1.5 to 3 times the weight of the bones (depending on the type of bones being used…)
- herbs and peppercorns, tailored to the type of stock
- Roast the bones in a heavy tray until thoroughly browned. Remove the bones and chill.
- Roast the vegetables in the fat that rendered from the bones until lightly browned. Remove and chill.
- Pour any excess fat from the roasting pan. Deglaze the pan with the dry cider or wine and reduce until au sec.
- Put the roasted bones and the cider or wine reduction in a stock pot and cover with cold water. Bring to a simmer very slowly, then hold at a gentle simmer for 24 hours.
- Add the roasted vegetables to the pot. Return the liquid to a simmer and hold for 45 minutes.
- Add the herbs and peppercorns. Bring the stock to a simmer and hold for 15 minutes.
- Strain the stock to remove the bones and vegetables. Chill thoroughly, then remove the solidified fat from the surface.