Add the lentils to a heat-safe bowl or large measuring cup. (Choose a large bowl or cup, as the water will boil. Space will help prevent it from boiling over.) Cover with 1 cup water. Place into the microwave and cook for 3 minutes, stopping every minute to allow the water to settle. (This, too, helps it from boiling over.)
Drain the lentils, which should be very soft.
Add the drained lentils to a blender with the marinara sauce. Blend smooth.
Warm the sauce and serve with a pound of prepared pasta or meatballs, grains, or other desired food.
