Cook brown rice and lentils according to package directions.

In a small saucepan combine small pieces of chopped apples and carrots (may also add onion and celery). Add enough water to cover. Cook until tender, reserving water.
Combine rice, lentils, apples and carrots in food processor / blender. Puree, adding reserved water until the mixture is desired consistency, for smaller babies, or chop as needed for older baby.