Heat the olive oil in a Dutch oven over medium heat. Sear the chicken until golden, then set aside. Stir in the onion, garlic, and red pepper flakes; cook until the onions have softened, about 4 minutes. Add the rice, and season with salt, pepper, and saffron. Cook rice until golden, stirring constantly, about 10 minutes. Stir in the tomatoes, green chiles, and chicken broth. Place chicken thighs on top, then bring to a boil, cover, and place in the preheated oven.
Bake for 1 hour in the preheated oven, then sprinkle the peas, pimentos, and olives on top. Pour in the water, but do not stir. Recover and continue baking until the chicken is fully cooked, about 20 minutes.