In a large skillet, toss together the olive oil, chicken, oregano, paprika, and a pinch each of salt and pepper. Cook over medium-high heat until the chicken is browned all over and cooked through, about 5 minutes. Stir in the balsamic vinegar and garlic, cook another minute. Remove the chicken from the skillet. To the skillet, add the bell peppers. Cook until soft, 2-3 minutes. Add the orzo and 2 1/2 cups water. Season with salt and pepper. Cook, stirring often until almost all the water is absorbed, about 10 minutes. Stir the chicken and olives into the orzo. Allow the chicken to warm through, about 3 minutes.Meanwhile, toss all the ingredients for the tomatoes together in a bowl. Season with salt and red pepper flakes. To serve, spoon the tomatoes over the chicken and gently toss. Serve each topped with feta cheese and tzatziki.