In a large oven-safe skillet, heat the olive oil over medium heat and sauté the diced onion for about 5 minutes until soft.
Add the minced garlic, diced red bell pepper, chopped kale, dried oregano, red pepper flakes, and kosher salt. Sauté for 5 minutes until the kale wilts.
Stir in the tomato paste and cook for 1-2 minutes.
Add the uncooked orzo, canned diced fire-roasted tomatoes, cooked chicken or chickpeas, and broth. Bring to a simmer.
Transfer to the oven and bake for 10-15 minutes, or until the orzo is soft.
Finish by stirring in butter, crumbling the feta cheese on top, then dust with fresh dill and a squeeze of lemon juice before serving.
Notes
This dish can easily be made vegetarian by using chickpeas instead of chicken. Leftovers reheat beautifully for a quick lunch.