Make the picadillo. See the detailed instructions in my Puerto Rican style Picadillo recipe.
Peel, chop & boil the potatoes. Bring a pot of salted water to a boil. Prep the potatoes by peeling and chopping into halves or quarters (depending on their size). Add to the boiling water and cook until fork tender, about 15 minutes. Drain and transfer to a bowl.
Mash & season the potatoes. Mash the potatoes until all of the solid chunks have broken down and a consistent mash is formed. Mix in the corn starch, sazon, and adobo seasoning until the potatoes resemble a dough.
Form & stuff the potatoes. Using a ½ cup measuring cup or small scoop, grab large balls of the potatoes. Flatten the ball gently, fill with a tablespoon or two of the picadillo. Carefully form the potatoes around the filling, adding an additional scoop of the potato mixture if needed.
Fry. Fry the croquettes in hot oil until golden brown and crispy all around. Transfer to a paper towel lined plate to drain any oil. Enjoy!