My mother grew up in Sri Lanka, but it wasn’t until she emigrated to the United States in the 1970s and started building a family that she began cooking her native cuisine in earnest. When I was old enough, I started paying attention as she prepared elaborate, traditional meals for my family. That’s when I learned about tempering.Tempering is one of the most valuable tenets of Sri Lankan cooking I learned from my mother. The process is quite simple. Whole spices, like cumin and mustard seeds, get a quick swirl in hot oil, toasting them just enough to impart big flavor in minimal time. This flavorful cooking medium is then used as the base for any number of dishes; meats especially get beautiful color when seared in oil heavily flavored by chiles, onion, curry leaves, and ginger. You can also use it at the very end of a recipe. Some of my favorite dishes get a splash of this flavorful oil before serving; it’s a dramatically delicious way to finish a dish.The versatility of the technique can unlock a whole new world of options at your dinner table. It’s a fast way to introduce a balancing element of bitterness, earthiness, or brightness to the simplest of dishes, making it handy for quick weeknight meals.These tempered sweet potatoes illustrate how transformative the technique is. Hearty, filling, and packed with the flavors of my mother’s kitchen—onion, ginger, and chile flakes—they’re my cold-weather go-to. While my mother made this dish with russet potatoes or Yukon golds, I like using sweet potatoes because they are both firm and forgiving, making them ideal for soaking up the chile-and-spice-laden oil.