Cook quinoa in chicken stock or broth per package directions and let cool, 15 to 20 mins
In a skillet saute ¼ cup chopped onions in the olive oil on medium heat, 3 to 5 mins until softened.
Add chili powder, cumin and garlic powder and mix with the onions about 30 seconds.
Remove from heat and add to the cooked quinoa.
Add the salt, 1 cup shredded cheese, black beans, and salsa to the quinoa and mix thoroughly.
Spoon the quinoa into the pepper halves and bake at 375° in a casserole dish or on a sheet pan for 30 minutes, covered with a lid or foil.
Remove from the oven and uncover, then place a pinch of the remaining cheese on each pepper half.
Place back in the oven, uncovered, for 8 to 12 minutes until the cheese is melted
Serve with onion garnish and a dollop of Greek yogurt.