Heat olive oil in a large skillet over medium heat.
Add chopped onion and sauté until translucent.
Stir in minced garlic and diced bell pepper, cooking for 2-3 minutes.
Add ground beef to the skillet, breaking it apart as it cooks.
Cook until the beef is browned, about 5-7 minutes.
Mix in the diced tomatoes with their juice.
Add sliced olives and raisins, if using.
Season with cumin, salt, and pepper.
Simmer on low heat for 15 minutes, stirring occasionally.
Serve hot, garnished with fresh herbs if desired.