Heat olive oil in a large skillet over medium-high. Add onion and green bell pepper; cook, stirring occasionally, until softened and beginning to brown, about 5 minutes. Add garlic and cook 1 minute more.

Push the vegetables to the sides of the skillet and add the ground beef to the center. Break it into large crumbles and let it sear undisturbed for 2–3 minutes, then stir and break into small pieces. Cook until no longer pink and the beef reaches an internal temperature of 160°F (71°C), about 5 minutes. Drain excess fat if needed.

Stir in the diced tomatoes with their juices, cumin, oregano, smoked paprika, red pepper flakes, salt, and pepper. Bring to a simmer and cook for 5 minutes to let the spices bloom.

Add the sliced olives, olive brine, raisins, and capers. Reduce heat to medium-low and simmer gently, uncovered, for 12–15 minutes, stirring occasionally, until the liquid has reduced and the flavors have melded. The picadillo should be moist but not soupy.

Remove from heat and sprinkle with fresh cilantro. Serve immediately over white rice with your favorite sides.