Marinate the Chicken: In a large bowl, whisk together 1 tablespoon olive oil, 1 teaspoon salt, ½ teaspoon pepper, the juice and zest of 1 lemon, 1 teaspoon oregano, ½ teaspoon paprika, 1 teaspoon cumin, and 3 minced garlic cloves. Add 1.5 pounds boneless, skinless chicken thighs and toss to coat. Cover and refrigerate for at least 30 minutes or up to 8 hours.
Cook the Quinoa: While the chicken marinates, rinse 1 cup dried quinoa under running water. In a saucepan, bring 1½ cups water or chicken broth, ¼ teaspoon salt (if using water), and 1 teaspoon olive oil to a boil. Stir in the quinoa, reduce the heat to low, cover, and simmer for 20-25 minutes or until most of the water is absorbed. Remove from heat and let sit, covered, for 5 minutes. Fluff with a fork before serving. (Yields about 3 cups cooked quinoa.)
Make the Pickled Onions: Thinly slice 1 red onion and place it in a jar or bowl. Pour in the juice of 3 limes and add salt to taste. Stir to combine and let sit at room temperature for at least 30 minutes. For deeper flavor, refrigerate for a few hours or overnight.
Make the Tzatziki Sauce: In a small bowl, stir together 1 cup full-fat Greek yogurt, ½ cup finely diced English cucumber, a squeeze of lemon juice, 1 teaspoon olive oil, 1 minced garlic clove, salt to taste, and a pinch of fresh or dried dill. Chill until ready to use.
Cook the Chicken: Heat a large skillet over medium-high heat. Add the marinated chicken thighs and cook for 9-10 minutes per side, or until golden brown and fully cooked (internal temperature should reach 165°F). Let rest for a few minutes before slicing or chopping.
Assemble the Bowls: Divide the cooked quinoa between four bowls. Top each with sliced chicken, a spoonful of pickled onions, and a generous dollop of tzatziki sauce.
Serve: Garnish with cherry tomatoes, extra lemon zest or fresh herbs if desired. Serve warm and enjoy!
