Heat a 12 inch skillet over medium-high heat.
Once oil is shimmering, add onions and peppers, and cover and cook, until softened and spotty brown, about 8-10 minutes. Stir occasionally. Push to one side of the pan.
On the empty side of the pan, add tomato paste, garlic, paprika, cumin, oregano, and ½ teaspoon salt.
Cook uncovered for 1 minute, then stir it all together.
Add in wine and cook until nearly evaporated, about 2 minutes.
Transfer to a slow cooker.
Season flank steak with salt and pepper, and add to the slow cooker.
Add in soy sauce and bay leaves.
Make sure steak is covered, and cook until meat is fork tender, 6 to 7 hours on low or 4 to 5 hours on high.
Transfer the steak to a cutting board, and let cool for 3-5 minutes, and then shred into bite-size pieces using forks.
Discard the bay leaves.
Stir shredded beef and olives into the slow cooker and let it sit for 5 minutes.
Stir in vinegar, and season to taste with salt and pepper.
Serve with rice.