Make salsa verde. In a bowl of a food processor combine cilantro, garlic, onion, green chiles, jalapeño, spinach and ¼ cup vegetable broth. Blend until smooth.
In a deep skillet heat olive oil, add dry quinoa and toast stirring for a couple minutes until golden on medium heat. Add salsa verde, cumin, salt and pepper and cook for 2-3 minutes until bubbly. Then add 1 cup vegetable broth, turn the stove to simmer and cook until all the liquid is absorbed, 15-20 minutes. Taste and season with more salt and pepper if needed. Stir in black beans, squeeze in lime juice and set aside. The quinoa should be slightly saucy (it will cook more in the peppers) and well-seasoned.
While the quinoa is cooking heat the oven to 375 degrees Fahrenheit. Spray or brush a 9x13 casserole dish with avocado or olive oil (or other non-stick spray). Cut the peppers lengthwise and remove the seeds.
Stuff the pepper halves with quinoa and black beans until all the stuffing is used up.
Place stuffed peppers in the prepared casserole dish, sprinkle with grated cheese and cover tightly with foil.
Bake for 35 minutes covered, then uncover and bake 10 more minutes (or more if you like your peppers very tender). If you want the cheese to be toasted, turn the broiler on at the very end for a minute or 2.
Serve with your favorite toppings: avocado slices, sour cream, hot sauce, salsa or more chopped cilantro.