In a large heavy saucepan, combine the carrots, mushrooms, soy sauce, sesame oil, lemon juice, water and lemon rind. Bring to a boil over moderate heat and cook, covered, for 4 minutes or until the carrots are just tender.
Add the black beans and cannelini beans, cover, and cook, stirring occasionally, over moderate heat for 8 minutes or until the beans are very hot and the liquid has thickened. Stir in the green onions and cook, covered, for 2 minutes or until they are slightly softened. Serve with brown rice.