Place a 3-quart saucepan over medium heat. Add the oil and bacon. Fry, stirring, until the bacon is crisp. Add the onion and cilantro. Continue to cook for 5 minutes until the onion is soft. Add the rice, tomatoes, oregano, cumin, salt, achiote, and pigeon peas. Cook for 5 to 7 minutes until the rice is opaque. Stir in the tomato paste and water and bring to boil. When all the water is absorbed, cover tightly and reduce the heat to low. Cook for 25 to 30 minutes until tender. Serve on a decorative platter and garnish with cilantro.