How to Make It
Process plantains, yautia root, and salt in a food processor until smooth, stopping to scrape down sides occasionally. Place mixture in a bowl; cover tightly with plastic wrap, and set aside.
Place raisins in a heatproof bowl. Bring rum to a boil in a small saucepan over medium, and simmer 2 minutes. Pour rum over raisins, and let stand 20 minutes. Drain.
Heat olive oil in a cast-iron skillet over high. Add beef, and cook, stirring until browned and crumbled, about 6 minutes Add onion, sofrito, garlic, and sazón seasoning, and cook, stirring often, until onions are very soft, about 5 minutes. Add broth, bring to a boil, and cook until mixture resembles cooked taco meat (wet but not saucy), about 5 minutes. Stir in raisins; transfer mixture to a bowl, and cool to room temperature.
Shape plantain mixture into 24 (3- x 2-inch) rectangles on a large piece of wax paper on a work surface. Spoon 2 teaspoons beef mixture down center of each rectangle. Using a small offset spatula or butter knife, fold the long side of the plantain masa rectangle over beef mixture. Using your hands, form a log, gently pressing to seal and making sure beef mixture stays in the middle. Carefully transfer logs to a wax paper-lined large baking sheet, and chill 30 minutes.
Heat oil to 330°F in a large Dutch oven over medium. Gently add 6 to 8 fritters to hot oil. Fry 30 seconds, making sure fritters aren’t sticking on bottom. (Gently loosen any fritters from bottom so they float in the oil, if necessary.) Fry until light golden brown and is cooked through, 5 to 6 minutes, gently stirring occasionally. Drain on paper towels. Sprinkle with additional sazón seasoning.