Orange lentils are a little smaller than their green and brown relatives, but they're the lentil of choice for thickening vegetarian soups and sauces. Orange lentils give you a small window of time between crunchy and mushy, so you have to time their cooking if you want to eat them as a stand-alone dish. An ice bath is in order to cool orange lentils after cooking if you want to use them in a salad, and you can simply cook them in a soup or sauce if you want to use them as a thickener.
Rinse the orange lentils in a fine mesh strainer until the water drains clear. If you want to use the lentils in a salad, fill a container or bowl with ice and top it off with cold water. Keep the ice bath in the freezer while the lentils cook.
Transfer the lentils to a saucepan. Add twice as much cold water or stock as lentils to the saucepan. Add aromatics, such as bay leaves and dried peppercorns, if desired.
Set the heat to high and bring the liquid to a simmer. As soon as the liquid starts simmering, lower the heat so it barely bubbles; you don't want orange lentils jostling against each other in the liquid or their skins rub off.
Cook orange lentils for 20 minutes and rain them in a mesh strainer. Add the lentils to a bowl and season while hot with kosher salt.
If you want to use the lentils in a salad, add them to the ice bath as soon as you drain them and let them sit for about half a minute. Spread the lentils out on a plate lined with paper towels and blot the tops gently to dry. Chill the lentils in the refrigerator for at least 30 minutes before using.
If you want to thicken a sauce or soup with lentils, add them just before you season the sauce or soup for the final time. Puree the soup or sauce with a stick blender or just simmer the sauce or soup until the lentils break down, about 20 more minutes. Stir to incorporate and season to taste.