Oooh, tough choice, both yummy.

For the polenta, you can cook it up similar to rice, then put it into a flat container and let it cool. It will solidify a bit. You can then cut it up and put it on the grill or roast it in the oven to give it a really nice flavor and texture. People often serve it with pasta-type toppings.

For the lentils, it's hard to go wrong with either a nice lentil soup or a cold salad. Lentil soup is comfort food for me. Lentils are easy to cook, they don't require pre-soaking like most legumes.