Make the marinade. In a large mixing bowl, whisk together 1 cup (240g) Greek yogurt, 2 Tbsp (30ml) olive oil, 1 Tbsp (15g) mayonnaise, 3 cloves of grated garlic, 2 tsp lemon zest, 2 Tbsp lemon juice, 1 Tbsp dried oregano, 2 tsp kosher salt, 1 tsp sweet paprika, and ½ tsp black pepper.
Marinate the chicken. Add chicken thighs to the bowl, then toss to thoroughly coat. Allow this to hang out on the counter for 30 minutes (if marinating longer, be sure to refrigerate). Essentially, let it marinate while you make the rice and salad, then cook the chicken.
Rinse rice. Before beginning, rinse the rice in a colander under cool water for about 30-60 seconds, or until the water runs clear. This helps remove excess starch.
Make rice. Heat 2 Tbsp olive oil over medium heat in a large saucepan. Add diced onion then cook, stirring occasionally, until softened, about 3-4 minutes. Add 2 pints cherry tomatoes, then season with ½ tsp dried oregano and ½ tsp kosher salt. Cook, stirring every few minutes, until the tomatoes begin to blister and pop. After 8-10 minutes, stir in 1 Tbsp tomato paste and 2 cloves grated garlic. Cook for about 1 minute more, then add 1½ cups white rice. Stir well, then pour in 2¼ cups (530ml) of water or broth. Raise the heat to medium-high and bring to a boil. Reduce to a simmer, cover the pot, then cook for 12-13 minutes, or until the liquid has fully absorbed. Fluff the rice with a spoon, then stir in 1 Tbsp chopped mint or dill (if using) and 1 Tbsp unsalted butter. Taste and adjust seasoning, adding more salt, pepper, or herbs if you like.
Make the salad. In a separate mixing bowl, combine chopped cucumber, red onion, 1 Tbsp (15ml) olive oil, 1 Tbsp (15ml) red wine vinegar, 1 Tbsp chopped dill or mint, and a generous pinch each of kosher salt and black pepper. Stir, taste, then adjust seasoning.
Cook. When ready, set a rack about 6-inches underneath your broiler, then set to high. Place the marinated chicken thighs in a single layer on a rimmed baking sheet. Broil on high for 6 minutes, then carefully flip each thigh over and cook for an additional 6 minutes, or until the chicken is fully cooked and reaches an internal temperature of 165°F (74°C). Transfer to a cutting board and cool slightly before slicing each thigh into strips.
Assemble. Divide rice between bowls, then top each with sliced chicken, a little cucumber salad, and tzatziki if using. Enjoy!