Begin by rinsing the chicken breasts and patting them dry. Zest and juice the lemon, mince the garlic, and chop your onion and bell pepper into bite-sized pieces. Measure out the rice, chicken broth, and spices to keep everything ready.
In a skillet over medium heat, warm the olive oil. Add the chopped onion and bell pepper and sauté for about 3-4 minutes until softened and fragrant. Stir in the minced garlic and cook for another 30 seconds to release its aroma.
Place the chicken breasts at the bottom of the crockpot. Sprinkle the dried oregano, salt, and black pepper evenly over the chicken. Add the sautéed onion, bell pepper, and garlic mixture on top. Then, pour in the rice and frozen peas. Pour the chicken broth over everything, followed by the lemon juice and zest.
Cover your crockpot and cook on low for 4 to 5 hours or on high for 2 to 3 hours. The chicken should be cooked through and tender, and the rice fully absorbed all the delicious liquid. Resist the temptation to lift the lid too often.
Once cooked, gently fluff the rice with a fork and shred the chicken breasts if desired or leave whole for serving. Garnish with chopped fresh parsley for a pop of color and fresh flavor. Serve warm and enjoy.