Heat the oven to 400°F. Line a rimmed baking sheet with parchment paper and lightly grease 8 cups of a standard muffin tin.

Rinse the quinoa under cold water. Add it to a small saucepan with the water and bring to a boil. Cover, reduce the heat to low, and simmer until the water is absorbed and the quinoa is tender, about 15 minutes. Let it stand covered for 5 minutes, then fluff with a fork and set aside to cool slightly.

Dice half of the zucchini and half of the red bell pepper into small pieces. Finely chop the onion. Cut the remaining zucchini and bell pepper into bite-size pieces for roasting.

In a large bowl, combine the ground turkey, cooked quinoa, egg, chopped onion, diced zucchini, diced bell pepper, oregano, garlic powder, ½ teaspoon salt, and black pepper. Mix gently until just combined.

Divide the turkey mixture among the prepared muffin cups, pressing it in lightly. Stir the ketchup and tomato paste together in a small bowl, then spoon a little over each muffin.

Toss the remaining zucchini and bell pepper with the cherry tomatoes, olive oil, and remaining ¼ teaspoon salt. Spread them on the prepared baking sheet in a single layer.

Bake the muffins and vegetables until the muffins are cooked through and the vegetables are tender with lightly browned edges, about 20 to 25 minutes. The center of a muffin should reach 165°F. Rest the muffins for 5 minutes before removing them from the tin, then serve with the roasted vegetables.