You can cook lentils in an instant pot or another pressure cooker. However, this is often not worth the effort as lentils cook quickly on the stovetop. Also, since different lentils have different cooking times, it is very difficult to know when they are ready in the instant pot, and there is a high probability that they'll either turn out mushy and overcooked or undercooked. For this reason, we recommend cooking lentils on the stovetop. It's fast, easy, and fuss-free, and you can taste the lentils easily to adjust your cooking time.