Why a whole chicken?
The combination of fat and gelatin-rich bones therein will give you the best shot at the most flavorful broth that, ideally, should have a little body to it. The bird can be whole or cut up. In the accompanying recipe, the meat from the chicken does not cook for a long time and therefore can be used as a soup component. About 2 pounds of chicken wings could be used instead. For the accompanying recipe, though, it's easier to detach the skin for that fried-chicken skin benefit.
In a SeriousEats.com kitchen test, the thinnest and lightest-colored broth was made with boneless skinless chicken breasts.
Why not start with a commercial broth?
Lots of home cooks do, of course. But some products have lots of additives, including potato flour, yeast extract and "natural chicken flavor," and those who are wheat-, dairy- or gluten-intolerant need to read the labels closely to see whether the broths were manufactured in a facility that processes those ingredients. And some of those additives make for a cloudy broth.
What makes a broth cloudy?
Generally, tiny protein particles will make a DIY broth cloudy. This happens often when the broth is brought to a full boil, so a state of "barely bubbling" is the way to go for clear broth. If cooked noodles or chicken sit in refrigerated broth for more than a day, they can start to break down into particles, too. Why do so many store-bought broths and soup bases contain yeast extract?
It's commonly used to add an "umami" characteristic, and it contains some naturally occurring monosodium glutamate (MSG).
Why no skimming?
The chicken spends less time in liquid in this recipe than in others. Without the skin, there's less fat and fewer impurities to rise to the top. Also, we're taking a tip from chefs here: Instead of skimming, we let the broth and its components cool in the pot, then cover and refrigerate overnight. This enhances flavor and makes for easier straining the next day.
Why add lemon juice?
A squeeze of fresh lemon juice is a guaranteed flavor brightener that's good for almost all soups. And it may help reduce the amount of salt you'll add for flavor.