In a mini food processor, pulse the onion, bell pepper, garlic and cilantro until all is chopped very small to make the sofrito.
In a large cast-iron pot, heat oil over medium heat. Saute the sofrito mixture, tomato sauce, chicken bouillon cubes, sazon, oregano, adobo, black pepper and alcaparrado for about 2-3 minutes until vegetables begin to release aroma.
Add the pigeon peas with it's liquid and 2 cups of water. When the water begins to boil, add the rice, stirring occasionally to avoid from sticking to the bottom of the pot.
Once the rice has soaked up all the water and begins to dry up, lower the heat to low. Cover and let cook for 25 minutes. Then, stir the rice carefully and cover for an additional 5 minutes.