In a large pot of lightly salted boiling water, cook the lasagna noodles 10 minutes, until al dente, and drain.
In a bowl, blend the ricotta cheese and egg, and set aside. Preheat oven to 350 degrees F (175 degrees C). Coat a 3-quart baking dish with cooking spray.
Spray a large skillet with cooking spray, and saute the onion, green bell pepper, and garlic until tender. Mash 1 can of black beans. Stir mashed black beans, whole black beans, and tomato sauce into skillet, and cook until heated through.
Arrange 3 lasagna noodles in the bottom of the prepared baking dish, and layer with 1/3 each of the ricotta mixture, black bean mixture, and mozzarella cheese. Repeat twice.
Bake 40 to 45 minutes in the preheated oven. Let stand 10 minutes before serving.