Rinse quinoa under cold water in a fine mesh strainer. In a medium saucepan, bring vegetable broth to a boil. Add quinoa, cover, and reduce to a simmer for 15 minutes. Let it rest for 5 minutes, then fluff with a fork.

In a mixing bowl, whisk together olive oil, lemon juice, garlic powder, smoked paprika, salt, and pepper. Coat chicken breasts in this mixture; marinate for at least 15 minutes.

Preheat grill to medium-high heat. Grill marinated chicken for 5-7 minutes on each side until cooked through. Let rested chicken cool, then slice.

Combine cherry tomatoes, cucumber, and red bell pepper in a large mixing bowl. Drizzle with olive oil and season with salt and pepper. Toss gently.

To assemble, scoop quinoa into bowls, top with sliced chicken, vegetable mix, avocado slices, and crumbled feta. Garnish with parsley.