Season the chicken. Pat the thighs dry.
Sprinkle both sides with salt, pepper, oregano, basil, and smoked paprika if using. Set aside while you prep the vegetables.
Prep the produce. Slice the zucchini, onion, and mince the garlic. If using cherry tomatoes, leave them whole or halve them for quicker softening.
Sear the chicken. Heat 1 tablespoon olive oil in a large skillet over medium-high.
Add the chicken in a single layer. Cook 4–6 minutes per side until well browned. Remove to a plate; the chicken will finish cooking later.
Soften the aromatics. Lower heat to medium.
Add remaining 1 tablespoon olive oil and the onion. Cook 2–3 minutes until translucent. Stir in garlic and red pepper flakes; cook 30 seconds until fragrant.
Build the sauce. Add tomatoes and a pinch of salt.
Cook 3–4 minutes, stirring, until tomatoes start to burst and release juices. Use your spoon to gently crush a few for a saucier base.
Add zucchini and deglaze. Stir in zucchini and pour in the chicken broth. Scrape up any browned bits from the pan—those add flavor.
Simmer with the chicken. Nestle the chicken thighs back into the skillet, along with any juices on the plate.
Reduce heat to medium-low, cover, and simmer 8–10 minutes (boneless) or 12–15 minutes (bone-in), until the chicken reaches 165°F/74°C and zucchini is tender-crisp.
Finish with acid and herbs. Stir in lemon juice or red wine vinegar. Taste and adjust salt and pepper. Sprinkle with chopped parsley or basil.
Serve. Spoon the saucy vegetables over the chicken.
Add Parmesan if you like. Serve with rice, couscous, crusty bread, or over a bed of greens.