Puree the beans in a food processor, until smooth. If they will not hold together as a thick, moldable dough, heat the beans in a non-stick skillet over low heat, stirring constantly for 5 to 7 minutes, to thicken.
Allow beans to cool for 20 minutes, stirring occasionally.
Add the red onion, cilantro leaves, lemon juice and salt; mix well.
Form the mixture into scant 1 tablespoon balls. Refrigerate for 30 minutes. Serve.