In a large skillet, heat the olive oil over medium heat. Add the bell pepper, onion and garlic and cook until softened, about 5 minutes. Add the ground beef and cook, breaking up the meat, until lightly browned. Add the tomato sauce, saffron seasoning, cumin, 1/2 teaspoon pepper and salt to taste.
Stir in the raisins, olives and sherry, if using. Simmer the stew, stirring occasionally, for about 8 minutes.