Season the chicken pieces with oregano, salt, and pepper. Heat 1 tablespoon of olive oil in a large skillet over medium heat, then cook the chicken until browned and cooked through, about 6 to 8 minutes. Remove from heat and set aside.
In a medium saucepan, bring the chicken broth to a boil. Stir in the couscous, cover the pan, and remove it from heat. Let it sit for 5 minutes, then fluff with a fork.
While the couscous rests, prepare the vegetables by dicing the cucumber, halving the tomatoes, slicing the red onion, and slicing the olives.
Divide the couscous among four bowls. Top each with cooked chicken, cucumber, tomatoes, red onion, and olives. Sprinkle crumbled feta over the top.
Drizzle the remaining tablespoon of olive oil and the lemon juice over each bowl. Finish with chopped parsley before serving.