What does it mean to let the butter's foam subside?
 Certain phrases have become part of the recipe vernacular despite giving little in the way of good guidance. Most of us, for example, have seen something like this in recipes that call for cooking with butter: “Melt the butter over medium-high heat in a medium saucepan. When the foam subsides, add the vegetables and stir.” Why does the butter's foam need to subside? It’s an indicator of temperature. Adding vegetables or meat to cold fat is a fast way to mess up a good dish. The ingredients soak up the butter rather than cook in it, and the finished dish can turn out excessively buttery and too moist on the surface. Hot fat, on the other hand, prevents sticking and encourages browning. But if a recipe does call for you to let the butter's foam subside, here's a rough guide: |
| Heat 2 tablespoons of butter over medium-high heat. Swirl the butter around in the pan. The milk solids will begin to separate out. The butter will sizzle and foam. |  |
| After another minute or so the foam subsides. The butter looks more like oil now, and it’s hot. At this point you might add eggs for an omelette. |  |
| For something like a sage butter sauce, let the butter go another 30 seconds or so to let it brown and take on a slightly nutty flavor. Like olive oil, butter has a low smoke point, so watch it closely. You don't want it to burn and smoke. If it does, rinse and dry the pan, then start over. |  |
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