Cook onion, garlic, and pork in a large nonstick skillet over medium-high heat 5 minutes or until browned, stirring to crumble. Drain and return mixture to pan. Stir in raisins and next 5 ingredients (through tomatoes). Reduce heat, and cook 5 minutes, stirring occasionally. Stir in olives. Spread about 2/3 cup picadillo mixture on bottom half of each bun; cover with top half of bun.