1. Prepare the vegetables and chicken: Start by chopping your onion, dicing the carrots and celery, and mincing the garlic. If using chicken breasts or thighs, cut them into uniform 1-inch pieces. This ensures even cooking.

2. Add ingredients to the slow cooker: Place the cut chicken pieces at the bottom of your slow cooker. Then, add the chopped onion, diced carrots, diced celery, and minced garlic over the chicken.

3. Incorporate the canned goods and grains: Pour in the rinsed quinoa, undrained diced tomatoes, and the rinsed and drained black beans. Make sure to rinse the quinoa thoroughly to remove any bitterness.

4. Add liquids and seasonings: Pour the chicken broth over all the ingredients in the slow cooker. Sprinkle in the dried oregano, dried thyme, salt, and black pepper. Give everything a gentle stir to combine the seasonings evenly.

5. Set and cook: Cover the slow cooker with its lid. Cook on the “low” setting for 6-8 hours or on the “high” setting for 3-4 hours. The chicken should be cooked through and easily shreddable, and the quinoa should be tender.

6. Stir in frozen vegetables: About 30 minutes before serving, stir in the frozen corn and frozen peas. Replace the lid and continue cooking until the vegetables are heated through and tender-crisp.

7. Check for seasoning and serve: Taste the stew and adjust the salt and pepper if needed. Ladle the hearty stew into bowls and, if desired, garnish with fresh parsley or cilantro.