Step 1

If you have a good cooking thermometer (you should!), heat the peanut oil in a small saucepan over medium heat to 275 degrees.

Step 3

If you don't have a thermometer, heat the oil until wisps of smoke start to appear - that should be 350 degrees or so - then remove from the heat and let cool 5 minutes. Your oil should now be about 275 degrees.

Step 5

While the oil is heating, combine all other ingredients except sesame oil in a heatproof bowl or jar with at least a 1-cup capacity.

Step 7

When your oil is at the correct temperature, pour a little into the chile mixture. It should sizzle on contact with the chiles, but they shouldn't blacken (though they may darken a bit) or smell burnt. They should, however, send up a gorgeous toasty aroma. If there's no sizzle, heat your oil for another minute and try again. If there is evidence of burning, let it cool a bit more. Otherwise, pour all of the oil over the chile flakes.

Step 9

The mixture should sizzle and bubble merrily for a minute, smelling delicious, and then subside. Set aside to cool. When the mixture is cool, stir in the sesame oil. The oil can be used right away, but is better after a few hours to a day. Store at room temperature in a small glass jar or other tightly covered non-reactive container. Ma la oil can be stored indefinitely, but it is best in the first few weeks. If it starts to taste rancid - which might happen if stored for a long time or in hot weather - toss it and make more.