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