Build the sofrito base: heat olive oil in a heavy-bottomed caldero or Dutch oven over medium heat. Add onion and cubanelle pepper and cook 3-4 minutes until softened. Add minced garlic and cook 1 minute more. Add the 3 tablespoon sofrito and cook, stirring, 2 minutes until fragrant and slightly darkened.
Season the base: add sazon, salt, pepper, and apple cider vinegar to the sofrito. Stir to combine. The smell at this point should be unmistakably Dominican.
Add pigeon peas: add the drained guandules to the pot and stir to coat in the sofrito. Cook 2 minutes.
Add liquids: pour in the coconut milk and bone broth. Add olives if using. Stir everything together and bring to a boil over medium-high heat.
Add rice: once boiling, add the rinsed rice and stir once to distribute evenly. Cook uncovered over medium-high heat, stirring occasionally, until the liquid is absorbed to the level of the rice - you will see the surface of the rice when the liquid is at the right level. This takes approximately 8-10 minutes. Do not over-stir.
Steam finish: reduce heat to lowest setting. Cover the pot tightly with a lid or with aluminum foil pressed directly onto the pot before adding the lid for a tighter seal. Cook 18-20 minutes without lifting the lid.
Rest and fluff: remove from heat and let rest covered 5 minutes. Remove lid, add fresh cilantro, and fluff gently with a fork from the bottom up. Taste and adjust salt.
Serve immediately alongside Puerco Asado or Glazed Ham.