Heat the oil in a large caldero or cast-iron pot over medium heat.
Add the longaniza and cook until browned, cooked through, and lightly crisp on the edges; remove to a plate and reserve.
Carefully pour off excess fat, leaving about 1 teaspoon in the pot.
Add bouillon, adobo, oregano, sazón, and black pepper; cook 30 seconds, stirring, to bloom the spices.
Stir in the sofrito, tomato sauce, and olives; cook 2–3 minutes until fragrant.
Pour in the water and bring to a boil.
Stir in the rinsed, well-drained rice; cook uncovered, stirring occasionally so it doesn’t stick, until most liquid evaporates and the surface looks slightly dry/glossy.
Return the longaniza to the pot and gently fold to combine.
Reduce heat to medium-low, cover, and cook for 25 minutes.
Fluff the rice, cover again, and cook 5 minutes more. Serve hot.