Rinse and drain black beans and reserve. Rinse quinoa thoroughly and reserve. In a large saucepan or soup pot, heat olive oil over medium heat and add onion, bell pepper, celery, carrot and garlic and cook and stir until onion is translucent, about 10-15 minutes. Add reserved quinoa, cumin, oregano, cayenne, salt and pepper and toss to mix. Add broth, stir well, cover, and simmer about 20 minutes, until quinoa nearly tender. Add reserved black beans and cook 5-10 minutes more. Taste for seasoning, stir in Meyer lemon juice and serve.