1. Preheat oven to 375 degrees F.
2. Cut the peppers in half lengthwise, and remove the white pithy ribs along with the seeds and stems.
3. Spray baking dish with olive oil spray and arrange peppers in the dish.
4. Spray a large non-stick skillet with the olive oil spray. Saute the onion and garlic over medium heat until it starts to brown. If the onions and garlic start to stick, add a splash of water or broth to deglaze the pan.
5. Add the ground turkey to the pan, cooking until lightly browned and breaking it up as it cooks. Stir in the black pepper, chili powder and coriander.
6. Next add the salsa, the quinoa and the rice, heat through. Remove from heat and stir in the chopped spinach.
7. Pack the turkey mixture into the pepper halves so that it's heaping, about a cup (see pictures). Sprinkle the tops with the cheddar cheese and bake about 40 minutes or until the peppers are tender. Serve immediately.
8. Modify for the Grill: Wrap the stuffed pepper halves in lightly oiled tinfoil and cook covered on the grill over medium heat until the peppers are tender (30-40 minutes).