Rinse quinoa under cold water in a fine mesh strainer. In a medium saucepan, bring vegetable broth to a boil. Add rinsed quinoa, cover, and 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 the mixture and marinate for 15 minutes.

Preheat grill to medium-high heat. Grill marinated chicken for 5-7 minutes on each side until cooked through. Let rest before slicing.

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

Assemble the bowl with quinoa as the base, topped with grilled chicken, vegetable mix, avocado slices, and feta cheese.