In a large stockpot over medium heat, brown 1 pound ground turkey, chicken, or lean ground beef, breaking it up with a spoon, until no longer pink (about 6–8 minutes). Drain excess fat and return the cooked meat to the pot.
Add the diced onion, minced garlic, and 1 1/2 teaspoons ground cumin to the pot. Cook, stirring occasionally, until the onion is just tender and translucent (about 3–4 minutes).
Stir in the drained and rinsed whole kernel corn, drained and rinsed black beans, crushed tomatoes, deseeded and diced jalapeño, the rinsed quinoa, and 1 1/2 cups chicken stock or broth. Stir until evenly combined.
Bring the mixture to a simmer over medium heat, then reduce the heat to medium-low. Cover the stockpot and cook until the quinoa is tender and the mixture has thickened, about 15 minutes.
Remove the pot from the heat and let it sit, covered, for 3–5 minutes to finish steaming.
Fluff the quinoa mixture with a fork, portion into bowls, and serve topped with the diced avocado.