Combine the oregano, garlic, salt and pepper with 1 tbsp. of olive oil and rub the chicken with it.
Heat 2 tbsp. of olive oil in a deep skillet over moderate heat. Brown the chicken lightly on both sides.
Add the chorizo, onion, green and red peppers and cook until the vegetables are soft, about 10 minutes.
Add the tomatoes and rice and cook 5 minutes more. Add the chicken broth and saffron, mix well, cover with foil and cook until the liquid is almost absorbed about 15 minutes.
Add the shrimp, cherrystones, mussels, and peas. Cover and cook until the mussels and clams are opened, about 10 minutes more.
Serve in a large shallow dish or in individual bowls.