01 - Preheat the oven to 425°F. Line a baking sheet with parchment paper.
02 - Toss sweet potato cubes with 1 tablespoon olive oil, salt, and black pepper. Arrange on the prepared baking sheet in a single layer. Roast for 25 to 30 minutes, stirring halfway, until golden and tender.
03 - While sweet potatoes roast, combine quinoa, water, and 1/2 teaspoon salt in a saucepan. Bring to a boil, reduce to a simmer, cover, and cook for 15 minutes. Remove from heat and let stand covered for 5 minutes, then fluff with a fork.
04 - In a small mixing bowl, whisk together tahini, lemon juice, water, olive oil, maple syrup or honey, minced garlic, salt, and pepper until smooth and creamy. Add additional water to reach desired consistency if necessary.
05 - Divide spinach or mixed greens among four bowls. Add a portion of quinoa, roasted sweet potato, cherry tomatoes, sliced red onion, and avocado to each.
06 - Drizzle each assembled bowl with lemon-tahini dressing. Garnish with feta cheese, roasted pumpkin seeds or sunflower seeds, and fresh herbs as desired. Serve immediately.