Trim and butterfly the chicken breasts (or cut into even 1" pieces). Pat them dry with paper towels and season both sides with 1/2 teaspoon salt, 1/4 teaspoon black pepper, 1 teaspoon dried oregano and 1/4 teaspoon smoked paprika. Drying the surface helps the meat brown quickly and the spices cling—browning develops flavor through the Maillard reaction.

Measure the rice into a fine‑mesh sieve and rinse under cold water until the water runs clear (30–60 seconds). Rinsing removes excess surface starch so the cooked grains remain separate rather than gummy.

Heat a wide, heavy skillet (10–12") over medium‑high heat. Add 1 tablespoon olive oil and swirl. When the oil shimmers, add the chicken in a single layer and sear 2–3 minutes per side until golden but not fully cooked through (internal ~150°F/65°C if using a thermometer). Searing builds flavor; cook only until mostly done because the chicken will finish cooking with the rice in the next steps and you want to avoid drying the lean breast meat.

Transfer the seared chicken to a plate and tent loosely with foil. Lower the heat to medium and add the diced onion to the skillet. Sauté 4–5 minutes until translucent and starting to color — this releases onion sugars for flavor. Add the minced garlic and toast 30–45 seconds until fragrant; toasting garlic briefly blooms its aromatics without burning (burnt garlic tastes bitter).

Add the rinsed rice to the skillet with the onions and stir to coat the grains in the pan juices and oil. Toast the rice 60–90 seconds, stirring constantly. Toasting dries the rice slightly and allows it to better absorb broth, giving a nuttier, more developed flavor.

Pour in the 720 ml low‑sodium chicken broth, add the remaining 1 teaspoon oregano, remaining 1/4 teaspoon black pepper and the 1/4 teaspoon salt, and scrape any browned bits from the bottom of the pan (these are concentrated flavor). Stir once, bring to a gentle simmer, then nestle the seared chicken into the rice, seam side down if butterflied. Spoon any accumulated juices from the chicken plate over the pieces. Cover tightly with a lid — a snug lid traps steam to cook rice evenly and finish the chicken.

Reduce heat to maintain a low simmer and cook, covered, for 15–18 minutes without lifting the lid. Lifting releases steam and lengthens cooking. After 15–18 minutes, remove the lid and check rice and chicken doneness: rice should be tender and liquid absorbed; chicken should reach 165°F (74°C). If rice needs 1–2 more minutes, re‑cover and cook; if it’s dry but undercooked, add 2–3 tablespoons hot water or broth and continue briefly.

When rice is tender and chicken cooked, stir in the frozen peas (they’ll warm through in the residual heat and keep color and texture), lemon zest and juice, and the chopped parsley. Taste and adjust salt and pepper. Rest, covered, for 3–4 minutes — resting lets the juices redistribute into the chicken and rice, and the flavors meld.

To serve, slice the chicken if you left breasts whole and arrange over bowls of herbed rice, spooning any pan juices over the top. Finish with an extra sprinkle of fresh parsley and an optional lemon wedge. The contrast of bright lemon and oregano with warm, savory rice makes this dish feel elevated while staying low in fat.