Rinse the quinoa under cold water to remove its bitterness.
In a medium saucepan, combine quinoa and vegetable broth (or water). Bring to a boil.
Once boiling, reduce heat to low, cover, and let simmer for about 15 minutes, or until quinoa is fluffy and the liquid is absorbed. Remove from heat and let it cool slightly.
Meanwhile, prepare the avocado boats by cutting the avocados in half and removing the pits. Scoop out a little bit of the flesh to create room for the filling.
In a mixing bowl, combine the cooked quinoa, black beans, cherry tomatoes, corn, red onion, cilantro, lime juice, cumin, chili powder, salt, and pepper. Mix well to combine.
Spoon the quinoa mixture into each avocado half, filling them generously.
Serve immediately, topped with optional Greek yogurt or sour cream and sliced jalapeños if desired.