Preheat your oven to 400°F (200°C). Peel and cube the sweet potato. Toss the sweet potato cubes with 1 tablespoon of olive oil, salt, and pepper. Spread them evenly on a baking sheet and roast for 25-30 minutes, or until tender and slightly caramelized.

Rinse the quinoa under cold water using a fine mesh sieve. Cook the quinoa according to package instructions, or boil 2 cups of salted water and add the 1 cup of quinoa. Reduce the heat to low, cover, and let it simmer for 15 minutes. Fluff it with a fork and set aside.

While the sweet potato and quinoa are cooking, heat a grill pan over medium-high heat. Season the chicken breasts with salt, pepper, and half of the lemon juice. Brush with a little olive oil (or use spray oil). Grill them for about 6-7 minutes per side, or until fully cooked (internal temperature of 165°F or 75°C). Remove from the pan and let rest before slicing.

In a small bowl, whisk together the tahini, remaining lemon juice, minced garlic, a pinch of salt, and enough water to thin out the dressing to your desired consistency (about 2-3 tablespoons).

Once everything is cooked, start assembling the bowls. Divide the quinoa evenly into four bowls. Top with the baby spinach, roasted sweet potatoes, sliced chicken breast, diced avocado, and crumbled feta.

Drizzle the tahini-lemon dressing over the assembled bowls and serve immediately.