Season the chicken. Pat the chicken dry and season with salt and pepper on all sides. This helps it brown well and stay juicy.
Sear for flavor. Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Add the chicken in a single layer and sear until lightly golden on both sides, about 2–3 minutes per side.
Don’t fully cook it yet. Transfer to a plate.
Soften the aromatics. Lower heat to medium. In the same pan, add the onion with a pinch of salt.
Cook 4–5 minutes until soft and translucent. Stir in the garlic, oregano, and chili flakes. Cook 30 seconds until fragrant.
Build the sauce. Add crushed tomatoes, broth, and tomato paste if using.
Stir and bring to a gentle simmer. Taste and add a small pinch of sugar or honey if the sauce tastes too sharp.
Simmer the chicken. Return the chicken and any juices to the pan. Reduce heat to medium-low and simmer uncovered for 8–10 minutes, stirring occasionally, until the chicken is cooked through and the sauce slightly thickens.
Add the feta. Sprinkle the crumbled feta over the top and gently fold it in.
Let it warm for 1–2 minutes. It should soften and become creamy in pockets but not disappear completely.
Finish and taste. Turn off the heat. Stir in chopped basil or parsley and a drizzle of olive oil.
Taste and adjust salt, pepper, and chili flakes. If you like brightness, squeeze in a little lemon.
Serve. Spoon over warm pasta, rice, or couscous, or serve with crusty bread to soak up the sauce. Garnish with extra herbs and a few more feta crumbles if you want.