1 1/2 cups olive oil or vegetable oil
3 tablespoons unsalted butter
5 to 6 shallots, peeled and sliced into thin rings
Heat the oil and butter in a saucepan over medium-low heat until it reaches 220 degrees F on a candy thermometer.
Reduce the heat to low, add the shallots, and cook for 30 to 40 minutes, until they are a rich golden brown. The temperature should stay below 260 degrees F. Stir the shallots occasionally to make sure they brown evenly. Remove them from the oil with a slotted spoon, drain well, and spread out to cool on paper towels. Once they have dried and crisped, they can be stored at room temperature, covered, for several days.