To make green bean baby food, start by trimming and washing a pound of green beans. Steam the beans until tender, then puree them with 1/4 cup of water in a blender or food processor until smooth. Season with a pinch of salt and pepper, if desired. This simple, nutritious baby food is suitable for infants starting around six months of age. Store leftovers in an airtight container in the refrigerator for up to three days.