Make Tzatziki Sauce: Grate cucumber and squeeze out moisture. In a bowl, mix cucumber with Greek yogurt, lemon juice, minced garlic, dill, salt, and pepper. Refrigerate for 20 minutes.

Prepare Vegetable Salad: Halve or quarter tomatoes, dice cucumber, and slice red onion. Toss with red wine vinegar and salt. Set aside.

Cook Quinoa: Rinse quinoa under cold water. In a pot, combine quinoa, water, and salt. Boil, reduce heat, and simmer for 15 minutes. Let sit covered for 5 minutes.

Marinate Chicken: Cut chicken into bite-sized pieces. Combine with harissa, honey, salt, and pepper. Marinate for 5 minutes.

Cook Chicken: Heat olive oil in a skillet. Add marinated chicken and cook for 7-10 minutes until golden brown and cooked through.

Assemble Bowls: Start with quinoa, add chicken, vegetable salad, tzatziki, feta (if desired), and garnish with mint and olive oil.