In a mixing bowl combine 1 tbsp lemon juice, 1/2 tbsp dried oregano, 1/4 tbsp paprika, 1/4 tsp ground coriander, 1/4 tsp ground cumin, minced garlic, 1/2 tsp salt, 1/4 tsp pepper, and 2 tbsp olive oil.
Add the chicken breasts to the marinade, toss to coat, and refrigerate for at least 10 minutes or up to 2 hours.
Heat a skillet over medium-high heat and cook the marinated chicken 4–5 minutes per side, or until golden and cooked through. Remove and let rest on a cutting board for 10 minutes, then slice into strips or bite-sized pieces.
While the chicken rests, make the sauce by whisking together 1/2 cup mayonnaise, 3/4 cup Greek yogurt, 1 tbsp sugar, 2 tbsp rice vinegar, 1 tsp lemon juice, 1/2 tsp salt, and 1/4 tsp pepper in a bowl; set aside.
Make the rice: melt 2 tbsp butter in a medium saucepan over medium heat. Add 1/2 tsp curry powder and 1/4 tsp cumin and cook 1–2 minutes until fragrant.
Add 1 cup basmati rice and toast for 4–5 minutes, stirring frequently. Pour in 2 cups low-sodium chicken broth, 1/4 tsp salt, and 1/4 tsp pepper, bring to a boil.
Reduce heat to medium, cover, and simmer for 15 minutes. Remove from heat and let sit, covered, for 15 minutes more, then fluff with a fork.
To serve, divide the rice among plates, top with sliced chicken, and spoon the creamy sauce over the chicken.