01 - Preheat oven to 400°F.
02 - Toss beet cubes with 2 tablespoons olive oil, 1/2 teaspoon salt, and 1/4 teaspoon pepper on a baking sheet. Roast for 30–35 minutes, stirring halfway, until tender and slightly caramelized. Let cool slightly.
03 - Combine quinoa, 2 cups water, and 1/4 teaspoon salt in a medium saucepan. Bring to a boil, reduce heat to low, cover, and simmer for 15 minutes or until liquid is absorbed. Remove from heat and fluff with a fork.
04 - In a small bowl, whisk together orange juice, 2 tablespoons olive oil, vinegar, Dijon mustard, honey, 1/4 teaspoon salt, and 1/8 teaspoon pepper until emulsified.
05 - Divide quinoa among 4 bowls. Top each with roasted beets, spinach, carrots, cucumber, avocado slices, pumpkin seeds, and feta if using.
06 - Drizzle bowls with orange vinaigrette just before serving.