Add the oil, onions, bell pepper, and garlic to a frying pan over medium heat and sauté until the onions are tender and starting to caramelize around the edges.
Your sofrito should look like this.
Add the oregano, cumin, cinnamon and bay leaves, and sauté until very fragrant.
Add the beef, tomatoes, wine, tomato paste, potatoes, raisins and salt and break up the meat and tomatoes using a spatula. Partially cover and simmer until the potatoes are tender (about 15 minutes).
Remove the lid and add the olives. Let the picadillo cook until most of the liquid is gone, leaving a thick sauce that coats the beef (about 10 minutes).
When the picadillo is finished, stir in the olive brine (liquid the olives came in) and adjust salt and pepper to taste.