Frozen rice or rice pilaf can be added directly to soups or casseroles. To serve as a side dish, you’ll need to add a bit of water over the rice to replace the moisture it lost in the freezer. Frozen rice can be microwaved on high power for 2-3 minutes. To reheat in the oven, spread the grains onto a sheet pan and bake in a 350°F for 20-25 minutes, or reheat in a pan on the stove top over medium-high heat.