Preheat oven to 425°F and line a large baking sheet with parchment paper.
Toss bell peppers, zucchini, red onion, and carrots with olive oil, smoked paprika, salt, and black pepper in a large bowl.
Spread vegetables on the baking sheet and roast for 25-30 minutes, stirring halfway, until tender and caramelized.
Combine quinoa, vegetable broth, and salt in a saucepan; bring to a boil, reduce heat, cover, and simmer 15 minutes until quinoa is cooked, then fluff with a fork.
Pat chicken breasts dry and coat with olive oil, smoked paprika, garlic powder, salt, and black pepper.
Cook chicken in a preheated skillet over medium-high heat for 5-6 minutes per side, until golden and internal temperature reaches 165°F; rest 5 minutes, then slice.
In a salad bowl, toss mixed greens and cucumber with lemon juice, olive oil, salt, and black pepper.
Assemble bowls with quinoa, roasted vegetables, sliced chicken, salad, avocado slices, and garnish with parsley if desired.