1. Cook the bacon in a medium skillet until crisp, then transfer to paper towels and drain.
2. Pour off all but 1 tablespoon of drippings from skillet. Add the onion and garlic and cook over medium heat about 3 minutes or until tender. Crumble bacon into a medium bowl and add onion mixture. Stir in the cream cheese, sour cream, horseradish, mustard, pepper, and salt until blended. Cover and refrigerate for 2 to 24 hours.
3. Remove dip from refrigerator and let stand at room temperature 1 hour before serving. Serve with vegetables and crackers. Makes 24 servings (1-1/4 cups).