It's A Mistake To Cook Sausages One Or 2 At A Time
In most cases, overcrowding your pan — like with bacon, for instance — yields poor results for whatever you are cooking. However, in the case of cooking sausages, the more the merrier! While it may seem that cooking with more room in your pan will give your sausage an even browning on all sides, this isn't the case at all. Cooking one or two sausages at a time can give you a higher likelihood of burning one side of your sausage. It's just one of those foods that burn quicker than you think.
So make it easier on yourself and cook however many sausages you need to feed the party all at once. By having the sausages packed in together on the pan, you'll slow down the cooking and everything will cook more evenly. Any moisture or liquid coming from the sausage will buffer the hot pan and essentially steam the sausages, making for a perfect even browning.
Cook your sausages over medium heat
We may be accustomed to seeing a deep char on hot dogs or sausages, but that doesn't mean that sausages should be seared on high heat. Any kind of sausage, be it a hot dog or bratwurst, has a very delicate casing that burns or rips when it comes into contact with a hot pan. Some suggest poaching the sausages in cold water until it comes to a boil on the stovetop before grilling or frying them. The only issue with this poaching method is that you'll most likely be boiling the sausage more than barbecuing it, which prevents you from getting a smokey flavor.
The best way to prepare sausages is to cook a lot of them at once over medium heat. Your sausages are most likely cold from the refrigerator, meaning that they will buffer one another from burning and heating too fast. The medium-level heat of the stove will slowly and evenly cook all of the sausages thoroughly. If you like the semi-steaming effect caused by having many sausages in the pan, you could even splash a little bit of water or stock in your frying pan.